Just relax, OP.
I know easy to say, I am not a man so can’t pretend I know what they would do/say but I am a woman who have sexual encounters with women of all body types and honestly it doesn’t one bit what your body looks like but it does matter a lot how confident you are and how comfortable in your own skin you feel. By the time sex happens, the person who has chosen to have sex with you has already decided that you are attractive to them. Just trust them.
Personally I have never seen a body that made me want to run off the room or that even made me feel one bit less attracted to the person. If I am sleeping with a woman it’s because I find her attractive irrelevant of what’s under her clothes.
The one thing that turn me off is lack of confidence or women who compare bodies. I get it. It’s hard to feel confident when you don’t like your body but if other people like your body, why don’t you? It’s yours. It created your child and believe it or not it’s beautiful no matter how stretched out or anything you might find negative it becomes/is. An apron wouldn’t turn me off but a woman who would want to hide under the cover and that I would have to spend a lifetime convincing that they are attractive because of it would absolutely turn me off and put me off of them.
Just believe that not only are you attractive but that he is attracted to you. What he or his ex looks like is irrelevant. I am quite fit and one of my ex is a Scandinavian model and yet I wouldn’t blink or twice about dating/sleeping with someone who is overweight or with an apron (and in fact happily have many times) because weight/body shape isn’t the determining factor of attraction.
Don’t try and look for reasons as to why he shouldn’t be into you and embrace the fact that he, indeed is, and allow yourself to have some fun!
(Honestly lack of confidence from other women is what has killed many budding relationships for me and it’s a shame because I was genuinely attracted to them and had they believed me maybe the story would have been different).
So learn to love your body and accept the reality that people who sleep with you are very much likely attracted to you and what bothers you simply doesn’t/won’t bother them.