How do I deal with a difficult mother-in-law who is suffering from cancer and my husband who refuses to see there is a problem?

I think you should sit both MIL and Hubby down and have a big heart to heart discussion. Make it plain what the rules are and what is expected of everyone living under your roof. I think keeping things out in the open is the best way to handle it.
PS before you get everyone together, make sure your husband knows you expect his full support.

How was it decided that your MIL should move in with you? You say that she is still relatively healthy - could she live in assisted living with extra help from you two? Who is handling all her care? If it isn't a "team" effort, your husband will never understand how many demands are placed on the primary caregiver.
You two need to sit down and make a game plan. How long will his Mom be there before you need to consider an alternative? At some point, you two will not have the medical expertise that will be needed. Have you considered calling hospice to see what they can offer? Ask her doctor about it. (btw, hospice care can take place anywhere)
Until you have a calm, rational discussion with your hub, where no one becomes emotional or accuses "badmouthing," nothing will change. Maybe if you went out of town to visit a friend and left the hub with the full responsibility he may see how taxing this is for you. Also, set a time limit for when you two will look for alternate living space for her.
I fear that this situation will make you physically ill. It is difficult to combine two households under the best of circumstances. With your history with your MIL, it may be impossible.
Have lots of talks with the hub. Counseling may be good too, if you are at an impass. Do it sooner than later.
good luck

The real problem here is you husband. You must be first in his life and something tells me his passive agressive behavior is not helping. I know, this is the way my husband behaves. When his mother was alive she could do no wrong. She was a very nice lady but intrusive in our lives about religious matters and how we raised our kids. He also has a sister who was very much like your mother-in-law. He never stood up for me. Let him do most of the work since she is his mother and you may see some changes. Good luck

You may want to point out to the hub that since he is so close to the situation it leaves very little room for perspective. That is why counseling is so important. If he won't go, you should go by yourself. You need to figure out how to deal with the situation until you two can resolve it. Many children are raised to think that they need to do everything for their parents regardless of how they were treated as children. You may suggest to the hub that his childhood issues may actually be getting in the way of getting appropriate care for his Mom.
In the meantime, you need to set limits. Inform the hub that HE will be taking Mom to the ER when she has "breathing problems." If he cannot get away from work, he will have to make arrangement for her to be transported to the ER until he can arrive. And follow through with it. You are jeopardizing your career, which he doesn't seem too worried about.
You are running interference between your hub and his Mom...and they are both taking advantage. Your MIL needs to be in an ALF. When she needs hospice, she can have it there. (btw, contact them...your MIL does not need to wait until her last days in order to qualify for it. Go online and look at the requirements. Cancer is one of the diseases on the list. Since she is healthy now, this might be the time to get her moved and start with the care.)
When you talk to the hub, tell him that you are going to look into a few ALFs just for information. Gather the information and narrow it down to one or two places. Then have your him and your MIL visit and choose.
Sometimes you just need to be proactive for yourself. If you continue to pick up the slack of caregiving for your hub and put up with the MIL's nasty behavior, this situation will only get worse. I hope the hub sees the light and starts to value you more.
good luck

I say, do move out. Let the husband see what he is up against. Life is too short to put up with these things and people. Don't move back until you husband (child, really) has developed a backbone and became a good leader in his family. If that never takes place, then so be it. The marriage wasn't worth saving.

What I am trying to say is that she most certainly fears death (most people do) and she feels vulnerable and alone. She knows she has cancer, she starts to think about it, she is alone and home, her fear rises and BAM...hyperventilation that she doesn't even recognize.

Amanda, reading through some of these posts and I am sad to see such a load placed on your shoulders. No you should not just suck it up. You are the daughter-in-law, not the son or daughter. Out of the goodness of your heart you are taking care of your mother-in-law. Does your husband have siblings? It is up to your husband as to how much he will allow your MIL to disrespect you. If he doesn't have the nerve to address this, it is time to find other arrangements for her. This is very unfair to you. I know some would have you feel guilty, but this woman has never treated you as a daughter.

Also, I feel guilty and selfish about the way I feel.

Tigerlilly, I do believe you are right. Hubby and I talked about it last night. What really made me think that it was anxiety was that she had one just before the CT last night.
I do think we ALL need counseling.

Amanda, I have had full blown panic attacks and I can tell you that during the attack she has no idea that it starts in her head. Then if people act dismissive it makes it worse. On the other hand you can't coddle the attack. There are a few tricks that might help her if you set them in motion before the attack. First make sure she knows that even though she is definitely feeling what she's feeling that it is adrenaline that is causing it, she can't die from it. If it gets to the point she passes out her body will take over and breath on it's on. Once she feels it happening she can breath into a small paper bag , she can also consciously force herself to count between inhales. For example: Inhale on a count to 3 , exhale on a count of 5 - counting slowly.
Also depending on where she has cancer that might worsen this problem.