It is not /u/FeelingsElevator job to save ex BFF. She may be a victim yes, but she is much more informed than most victims. She has already proven she won't listen to OP. Even though ex BFF is the person who originally helped her out. Ex BFF has become a co-abuser. And it's hurtful to even suggest that OP needs to save her, because it's just opening up OP for more and more abuse, and OP doesn't actually have any power in this situation.

Telling ex BFF's friends and family is going to look like stirring up drama. You can't pressure someone into leaving their abusive partner. It needs to come from them, and they need to be ready.

Stop trying to make OP feel bad for not wanting to deal with any more abuse after an extremely traumatizing situation. OP has to prioritize their own mental health, and they're not a monster for doing so.