Boyfriend drama is destroying my friend group
So basically I'm in a trio and one of my friends started 'talking to' this guy who's a major red flag. He cheated on his ex, went to write an exam high, body shamed girls at school, and regularly makes racist and misogynistic jokes (I know lots of teenage boys have edgy phases but still)
The last straw was when my other friend (who isn't seeing him) got into a fight with him over all the shit he's done, and he was very aggressive towards her. Not physically (since they fought over the phone) but he outright threatened her and said some fucked up shit. My friend who's seeing him promised to break things off with him, but today she ended up making that relationship official. What's more, SHE proposed to HIM. And I tried to remind her of the kind of person he is, but she says that he's helping her get over her ex, and "He's a good person deep down and he's trying to change". Naturally my other friend is pissed and now they aren't talking to each other.
So idk what to do here. My friend is genuinely a nice person and I don't know why she's dating a guy like that. Advice would be appreciated
Dinner was a homemade bean wrap