Liv, it's funny that you mentioned the narcissistic sponge living off your income for years, and taking work in your field. The same thing happened to me. In fact, XH made less than half my salary for over ten years of our R. When he couldn't really break into my field, he began to disparage it. Now, however, he tells people that one of his lines of expertise is my former field. Whacked is the best word for it.
He has told people that I married him for his money. Funny, it all seemed to be my money.
Decide what kind of R you want with him, then live that. It's all you can do.