I'm exhausted taking care of him and I want to move on with my life. What do I do?

Firstly start the proceeding for divorce and separate your finances
you can be getting a divorce and live under the same roof as long as you can prove you are separated. You can settle all financial matter and common property and then when the papers are signed, leave

Write your self two lists of reasons why you should stay and reasons why you shouldn't. You say you were about to leave, so your reason for staying sounds singular and linked to feeling you owe him something - but you didn't feel those things before. Priorities change but remind yourself of what they all were on both sides, and if you decide to leave ensure you have made arrangements for care needs he actually has, not ones you feel 35 years entitles him to - and get on with your life. Count any additional supports he has given you over the years as part of being married for 35 years, but if it is just 35 years then that is only one factor - its not easy to make lists of pros and cons, but just because he got cancer doesn't delete out all the things that were making you consider leaving.

My mother was end stage COPD with asthma, using oxygen when necessary, then we moved her from living in city near the sea, into the countryside and I have ordered nil nebuliser chemicals, no broncho dilators, no steroids and just two steroid inhalers in 2 and a half years - not sure if the air makes the difference or just not having a Dr who panders to her on it. its something that a move CAN make a huge difference to, not in all cases but worth discussing with Dr.

I think it may be helpful for you to find a place to put him in respite care for a couple of weeks and take a vacation. Use some of the time to just have fun, do things you haven't been able to do in awhile. Then use some of the time to sort through your options. It is not a good idea to make life changing decisions when you are in such an emotional struggle. A good counselor can help you work through the emotional issues attached to the affair and your feelings of being trapped. Maybe you can move forward with a life for yourself and still help him during this final stage of his life too. Do you have children together? Maybe they can help with care. Wishing you all the best!

You have limited emotional energy right now, so maybe don't spend it on a divorce unless you get professional financial counseling that says it's the best option to preserve funds for your own present and future care.

Look into hospice or place him in LTC soon for your own sanity. Do you have kids nearby? If so maybe you can enlist them to provide temp help until you catch your breath.

I took responsibility for the care of my jerk stepFIL who had Parkinsons, no money because he was lazy, deep in debt and wouldn't give anyone PoA. We tried to provide adequate care for him but he would't even cooperate yet expected us to be at his beck and call. So I allowed him to become a ward of the state and he died alone in a crummy facility. There were days that I did feel guilty for that, but then I remembered that that was the retirement he had "planned" for. Get good professional advice and then start living.