I would say…

“ hey, you know, I have something I need to tell you. I don’t know how else to say this but when you insulted me about my weight during our arguments, and the fact you never went down on me and it just always causes fights, I just don’t know if I want to have sex anymore, I know you have apologized and have told me I’m sexy, but I just can’t believe you anymore and I am just so deeply hurt by what you have said that I cannot forget it and it effects my desire to be intimate with you”

Or something like that.

So the main thing is that if he gets angry or blames you or tries to turn it around on you for bringing your feelings to the table, you should leave.

A conversation about feelings should never end in an argument.

But if he wants to fix it and seems apologetic and remorseful, then I think you guys can decide from there where you want to go with the relationship or decide whether it’s too broken to fix.

Edit: more details, clarification.