So my sister is having a ton of shit with the ex-fiance, and seeing as how I'm basically the family…

So my sister is having a ton of shit with the ex-fiance, and seeing as how I'm basically the family therapist, she's telling ALL about it. First they broke up, then they were in an "open relationship" and now they're broken up again "but still best friends." He doesn't want a relationship, and she desparetly wanted to keep him so she said they could see other ppl as well, and then backed out so he dumped her.

I am DESPERATELY trying to put it lightly that he doesn't really want her anymore, he just wants to be a slut, and that she needs to let him go point-blank. But she just ain't listening. He's been with like 50+ ppl before her and that's like..gross and I'm not sure how he doesn't have any diseases but whatever..i know she loves him and I know she wants to be with him, but he's obviously stringing her along and I can't stand to see that. I dunno what to do tbh