My best friend is so insecure and she takes it out by being mean to everyone especially guys?

My best friend has a "boyfriend", that I would classify more as an on and off again f*ck buddy. He basically calls her when he wants sex or her emotional love for him, then once he's done he ignores her and calls her names (slut, whore, b*tch). Yet at the same time, he always makes her promise that she won't sleep with or even talk to other guys when he cheats on her the second hes done with her. She'll listen to him completely, she's seriously like his puppet when she's with him, then once he dumps her again she'll be like "let's find me a new guy", but then go rushing back to her "boyfriend" the first time he calls her. I have noticed that when she talks to guys that aren't her "boyfriend" she acts like shes interested then is like "Ew, Jacob keeps texting me he won't go away." And she purposely leads them on saying stuff like "I'm going to make him spend all his money on me. I'm so mean to him hahaha" I thought it was funny when I first met her, but now I realize that she's just doing this because she's insecure. It's really sad how mean she is to some of the guys, and she talks bad about all the people she hangs out with, maybe even me. She also tells everyone how 'hot' she is all the time and how many guys want her. But at the same time she says her body is gross until she gets her breast implants since she has wanted since she was like 10. I don't know what to do. She's one of my only friends, but her meanness and trash talking to people is getting so annoying to me that I get irritated while I'm with her and can only hangout with her for a short time. I love her, but its hard to love someone that's so mean to everyone, and I'm not even sure that she doesn't trash talk me.