Best friend talking to my ex

So..one of my best friends who's like an older sister to me is talking to my ex. She talks to two of my exes and tells me about them. She knows I'm trying to move on. The one ex she is good friends with and we met through him but they didn't become close until after we broke up because he's still legally married. Long story lol but he lied to me about it and she doesn't seem to think he was wrong for it. And it bothers me but I know I can't tell her what to do or who to talk to. But It brings up those feelings that I don't want and she doesn't see him or either of them the way I do or did. It's hard I don't want to lose her as a friend but I don't know if I can handle her talking to both of my last exes. It messes with my head and mental health. I'm working on my mental health and I'm trying to elimate negative things in my life and I don't know what to about it. It's pulling me back to that and I need to go forward. I know I should just tell her but I'm scared of her reaction. Tough situation I know. But any input with be great from you ladies😊