If you determined to stay in the situation, then you need to learn to recognize provocation as exactly that--something said to get a reaction from you. It only has the value and the weight that YOU give it. The more reaction he gets, the more he will provoke. I know that you have said if you ignore it, he just pushes harder--this is evidence that his goal is to get the desired reaction. Try to breathe your way through these times, continue to ignore, and remember that he is very sick and likely can't help himself. But you can.