If you haven’t, maybe work it that you’re not having a mastectomy (not that that is any less respectable) but if his monkey brain is so hung up on the size of your boobs, having a c/d cup is perfectly palatable I think to many women and still the kind of “bragging rights” (gag) size to men, if that’s a size you’re comfortable with. I hate that this is even something you should have to debate with your partner, but if you must, remind him you’re not a show pony/fuck doll. You will still have nice tits when it’s over, and if he cares more about your abnormally large breast size than the decreased quality of everyday life you’re facing, I think that demonstrates what he really values about you.