Hey Katie,
If your not happy get out of the relationship as quickly and as easily as you can. If you love this guy want want to make it work, then try to come to some sort of understanding with the mother problem. It’s a tricky spot to be in but it sounds as if this relationship isn’t all that serious anyways? So maybe just ride it out until it’s not fun anymore and then move on. Idk. I wouldn’t worry so much what someone said about me. Just be yourself and have a good time.
Good luck hang in there.