OH man. My first knee jerk reaction is this is a trap. Run the other direction. He has proven himself to be a very unstable person, and I would only believe he is not over the course of a very long time. I would also not count on him being there for when I need to make plans, as alcoholics are notorious about being unreliable, as we all know.
Just don't put too much stock into this. You are 100% right, you need to stay healthy and in the past he has not helped with that.
I say this with kindness b/c I know how hard this is for you.
Sending lots of love and many hugs! XXX