SOMEONE PLEASE HELP

Okay so like my boyfriends ex girlfriend literally just texted him and said that she still had feelings for him and they broke up over a year ago. He told her that he just liked her as a friend and that he really liked me, but then he literally called me because I was freaking out and he was like I’m not gonna hang with her alone but would you be okay with me and her hanging with a group and I said yes because I dont want to be the jealous gf and I really do trust my bf I just don’t trust her because hanging out with her is going to intensify those feelings that she has for him and I’m scared that he might start gaining feelings for her too.