I am so sorry for what you are going through Dotty and Rex. I have been in your shoes and it is the hardest thing imaginable to witness and be a part of. Just the fact that you are still standing is a testament to how wonderful you are.
As hard as it is to take, your husband probably feels you are the safest person for him to vent his anger on because he knows that you will still love him no matter what. And I am sure you know, that when cancer gets into the brain, the person is no longer the same. Sometimes you just have to tell yourself this is not the actions that your husband, it is the cancer taking over. I was the one without the illness and I even yelled and screamed at my poor husband at times, the stress of the situation is beyond what any loving couple should ever have to go through.
Just try to love and be loved, and when you can't, don't beat yourself, or him, up about it. You are both doing the best you can do in an awful situation.
Sending much love and peace you way xxoo