Is there any way to anonymously warn someone about an abuser?

Unfortunately, I don’t have their email, only their FB page. I fear for this woman’s safety and wish someone had warned me but don’t want to draw the ire of the abusive ex or compromise my current relationship by “starting drama.”

I know a lot of people are going to tell me to move on and mind my own business, but I’ve been having bad dreams about this woman getting hurt. I’m not jealous but rather just very concerned about someone’s safety and can’t countenance standing by while he rapes and abuses another partner.