We have been having difficulty with communication. What do I do when he gets angry at me because I can't understand what he wants?

Ask his doctor to prescribe him medication for the aggression and keep him in a more relaxed state. It will help.
I've worked with many elderly people with Alzheimer's/dementia who often became very aggressive and even violent at times for many reasons. Sometimes it was out of frustration because they couldn't express themselves and other times it was for whatever reason, God only knows what.
One thing must always be so. You can never let a situation with an Alzheimer's/dementia sufferer ever escalate for any reason. Tell them everything is fine and then temporarily ignore them. Completely ignore them. Don't talk, don't look at them, don't anything for a bit. If you're alone in the home with him and there is no one else with you, this is the only action you can take to try and stop the situation from becoming dangerous.
If your husband is getting physical like you've said, then your situation has become dangerous already.
In truth you really don't have a whole lot of options. You can put your husband in a care facility which is where he belongs at this point. Or he will have to be medicated to where he is unable to physically strike at you. Bring in some outside caregivers to help you with him. Hire privately because you can negotiate the wages that way. You can't when it's agency help.
Of course you want to do right by your husband and don't want to put him in a care facility if it will cause you financial hardship.
Your safety has to be the top priority though. If you're in danger, call 911. Don't have any shame about it because if something happens to you, your husband will get put in a nursing home. The police and an ambulance will come and take him to the hospital. The hospital staff will send a social worker to speak with you and they will even help get him on medications to keep him calmed. Please don't neglect your safety and wellbeing.
Someone on this forum, I can't remember who made a great statement about caregivers in situations like yours.

"Don't light yourself on fire to keep someone warm".

Linda, my aunt was convinced that she and she alone could care for my uncle with dementia.

It was only when one of my cousins discovered that his poor mom was being beaten black and blue (my uncle wanted the key so he could go wander on the nearby highway) that my uncle was admitted to Memory Care where he lived quite happily for several years.

Sadly, my aunt dropped dead of a massive heart attack shortly after he was placed: she continued to "take care of him" every day in memory care.

I assume that you've visited an eldercare attorney and ate telying on solid legal and financial advice and not simply "what you've heard".

Medicaid will NOT leave you impoverished.

You are admitting that you're burned out, that he's now getting violent, yet because of financial reasons you don't want to place him in a memory care unit, where he belongs. Things that make you go hmmm.....
Do you at least have some hired outside help coming in, to give you a break once in a while, as taking care of yourself is just as important as taking care of your husband? You can't do it all yourself, as you are finding out.
My husband lost his ability to speak after having a massive stroke at the age of 48. He did eventually regain a few words and some short sentences, but having a conversation with him was difficult, as I couldn't always figure out what it was he was trying to tell me. If after a good bit I couldn't figure it out, I would tell him so, and that for now we just needed to drop it, before we both got upset over it. Sometimes that would work, and sometimes I just had to walk away from the situation before I got upset with him, as it wasn't his fault, and he would get mad at me because I couldn't figure it out. I had to tell him many times that I was not a mind reader. It's hard. I know. But it's not worth getting in a fight over. Especially if he's getting physical. My husband never did that, for which I'm grateful.
And as my husband got older his comprehension of the spoken word got worse as well, which made things interesting to say the least.
You must now do what is not only in the best interest of your husband, but also what is in the best interest of yourself as well. I wish you the very best.

You can be protected financially. Medicaid allows assets to be split. Your husband split being spent down and then Medicaid applied for. You become the Community Spouse remaining in the home and having a car. You will get enough to live on. That could be part or all of you monthly combined income of SS and any pensions. Depends on how much u need to live on. You will need a lawyer for this so have a consult with one well versed in Medicaid.

If your husband hits you, call the police. He may need to be placed for a Psychic eval. They will give him or adjust his meds.

Is your husband immobile?
Realize that your role as a caregiver is to keep him independent as long as possible.

Understand that it is your right to walk away from any disagreements before they start. Step outside. Or say you will be back after going to the bathroom.

It is not your role as a wife or caregiver to be ordered around. Avoid being ordered around, and allow him to go without his every need being met.
Not to punish him and not to neglect him, but to allow for his independence.

It is obvious from your described situation that you still see your husband as he was, and you also see as he is now. Unfortunately the “was” has more weight with you. He is no longer who he was. If you get angry you are only going to hurt yourself, and may cause him to hurt you. You need to adjust your roles and how you interact with your husband. Start looking at your husband as a helpless person/child who needs your help and will do things you do not understand. At the very least, if a situation might become violent, you need to walk away from it, but do not walk away mad. Make off like you forgot something, make a phone call, go to washroom, and cool off. Come back later and do not bring the disagreement up. He will probably have forgotten it as well. You need to work smart around his new undesirable behaviors. He is no longer your peer.

My mother would become so frustrated as she increasingly couldn’t control her mind. It wasn’t anything to take personal when she lashed out because she couldn’t come up with the words. I learned to “reset” her. I would change my tone from hers to happy & carefree with a sentence like Oh look outside, it’s a beautiful day! Would you like an ice cream cone or let’s go sit on the porch! As soon as my tone changed, she would hesitate, forget her previous mood & change along with me. When I hired aides to stay with her & they didn’t do this, my mother developed habits of escalating frustration with hitting. I had to change her aides when I discovered it because it was taking her down a negative road. Also too many words are confusing. I found upbeat, to the point words were easier for her & kept her in a lighter mood. If you have a good hospice team in your area they can stop by to help on a schedule. My mother can’t communicate much anymore & is mostly bedridden but she’s as content as she can be & doted on. It does take a lot of adjusting to get meds right & behavior management working but it’s possible to have a peaceful environment where their needs are met even before they ask & they feel secure. Good luck ❤️

You cannot prevent "it" from happening again. Your husband's brain is broken. You have no control of where this disease takes him and what "it" may be next. You only have control over how you react.

That said, it's time to, at the very least, ask his physician for medications to help keep him calm. For example, risperidone and olanzapine reduce aggression and are typically tolerated well. That may enable you to keep him home longer.

Equally important to your safety and financial wellbeing is bringing in help at home so that you can take regular breaks including, perhaps, putting him into respite care for a week or two once or twice a year. But that only will work if he is calm.

His needs are only going to increase. And you are already burned out. Your needs are equally as important as his. Things need to change if you are going to keep him home and be safe with him around. He is not capable of participating in making big decisions anymore. Only you can decide how they will change.

I’m sorry you are going through this.

I would reach out to his neuro/primary and even ask for a nuero psych consult. They have better experience and understanding in medications that may help him.

This is so hard for you and you need to make sure you do not get hurt. Even if he qualified for the aides or care it would also endanger them. I do not have dementia experience but I have seen outbursts from infections and stroke and the neuro psych did help a lot. Maybe that will even allow you to get help as you won’t be worried when he is with others. Keeping you in my thoughts

Your husband may be experiencing Sundown Syndrome. This confusion happens in the evening when a person starts getting tired, lengthening shadows make things look "different," and the person with dementia may not be able to handle any frustrations,

A few things to try:
Turn on more lights in the late afternoon.

Keep your husband on a consistent schedule.

If he is getting up at night, he may benefit from a sleeping medication.

If you notice he is more agitated with violent outbursts, he would benefit from seeing a geriatric psychiatrist and maybe anti-anxiety medication.