Abuse isn't always physical or obvious. I think this relationship always was and continues to be somewhat abusive to an extend, even if not obvious.

But it's too late now, you are where you are and you are doing things because you are a nice and kind person.

If you continue helping him, you can treat it as volunteering for people who cant show appreciation ( severely disabled or very elderly etc). You just do it out of goodness not expecting appreciation. Can you get appreciation from somewhere else if you aren't getting it from him?