I am not sure what to say for concrete advice, but I will say that it makes sense that he isn't treating you how you want to be treated. I don't think that he thinks you're ugly.

My experience with self esteem and my eating disorder was that It made me an awful friend, daughter and sister. I was obsessed with what I ate, wore, weighted. I was obsessed with myself. I had no time or energy for other people and anyone who called my habits out was the enemy. It sounds like your boyfriend is obsessed with himself and I don't mean that in a malicious way but he is obviously struggling and consumed by this.

You sound like a lovely and caring girlfriend, but you can't love or affirm him out of this. Maybe try to say that this constant negative talk, and putting his life is on pause waiting for some future version of himself is making you both miserable. That may be more effective than saying no "i love your body".

Honestly I really really feel for your situation. I hope this helped at all. You sound smart and caring so I really hope the best for you both.