8months prego & sex /venting/

So it’s gotten to the point where baby is big and in the way and I just don’t like the feeling of it when we are intimate. We tried going slow and I just felt soooooooo unattractive and awkward and my SO would try to go faster/harder and I’d have to stop him. We’ve been through relationship issues with infidelity and other things, I just don’t want to have sex and I’m terrified they will cheat again. I have like zero self esteem and I’m falling apart inside.