should i warn her?

so i have this kind of friend, we’re more just friends of friends, like i don’t know her super well. but she’s a very kind girl. she just started dating my ex boy best friend. long story short we aren’t friends anymore because he made some creepy comments and became controlling and overbearing because he had a crush on me and i had a crush on a different guy. he’s very toxic and has not grown as a person since we stopped being friends. he has gone through several girls one after the other, and they all end because of his bs. i want to warn her but it is most definitely not my place. what do i do? if i were in her place id wanna be warned but i feel like she will shove me away because she might think im trying to sabotage their relationship