My boyfriend and his ex were best friends before we started dating. I was somewhat uncomfortable with this so he agreed to stop seeing her for the time being. Fast forward a few months and now she's constantly asking him to hang out, asking him to do little favors for her by letting her borrow things and stuff. He had a falling out with his guy friends before we dated and she is his only friend now (besides me). I've told him I hate it that they talk and see each other because I feel like she still has feelings for him (he doesn't) but he says he shouldn't push someone away that's always been there for him. She always makes him feel bad when he doesn't hang out with her or talk to her. I love him and he gives me 100% attention but I don't know if I can deal with this. Am I being selfish by trying to get them to stop communicating or is he selfish by not putting my wishes first?

I think his ex is still have feelings for him. You should talk to your boyfriend about this. Nothing wrong with helping and talking time to time for friendship but hanging out with her is not good. You should made this clear to him.