Should I say something?

So my last relationship was really really toxic. He would constantly put me down and make me feel bad for wanting him to spend time with me apart from his video games. He would scream at me in front of his friends, to the point that even they would tell him he needed to stop. He cheated on me with his ex, who I later went to lunch with and found out he had lied to her and told her that we weren’t together. Overall it was just a really mentally abusive relationship. Well today his new girlfriend sent me a friend request on Facebook. My question is, should I send her a message and warn her about him? My intention is not to cause problems in their relationship, I just wish somebody had been there to tell me about him at that point in my life because i’m genuinely much more mentally messed up than I was before him.