My Best Friend Is Cheating on Her Boyfriend

And because she's my best friend I'm supporting her. I don't support what she's doing though. I haven't been egging her on or anything. But she's my best friend. She feels like shit, so I'm telling her it's okay. I'm telling her that even though she did a bad thing, it doesn't make her a bad person and I will love and support her no matter what. But she wants to hang out with this guy (the one she cheated with) again, and I'm just so frustrated. I told her that I personally thought it was a bad idea, but I feel like that's all I can do. I kinda feel like she's spiraling in life right now and I just want to be here to help her. I'm just frustrated right now and wanted to vent, sorry ladies!