Oh god this is tricky. But to be clear none of this was your fault.

It is highly unlikely she will be receptive to any message from you. So the most sensible thing would be to leave it. But I can see why you might want to send a message.

Do you have any shared contacts with this woman? What about messaging ‘X is a scary man. First sign that things aren’t right please consider leaving for your own safety’ and then blocking so it doesn’t turn into a dialogue?? But does he still have your number, know where you live? You have to put your own safety first.

Thinking of you.

Clare's Law is a deeply flawed piece of legislation that definitely isn't a catch-all for alerting women to violent tendencies in a partner, unfortunately, so even if you had reported him there would be no guarantee that it would have made a difference to subsequent partners. Firstly, the new girlfriend would be highly unlikely to request information under Clare's Law unless she had already spotted signs that he might be abusive anyway. And secondly, there are limits to what the police can/will disclose, so simply making a report about him alone wouldn't necessarily be enough for him to be flagged as a risk under Clare's Law. So please don't feel guilty about not making a report. You had more than enough to deal with at the time, escaping from your awful situation.

I do understand this dilemma. I was a victim of domestic abuse and I have wondered myself what I would have done if I'd discovered my ex had a new girlfriend, because I wouldn't want any other woman to go through that. Would I have contacted her? I don't know. Ultimately, think back to being in the early days of a relationship when it's all new and exciting and you're being love-bombed by someone and they're acting like the most perfect man in the world. If you really had got a message from that person's ex saying 'Just so you know, this man is abusive' would you honestly, hand on heart, have thought they were being sincere? Or would you have thought she was, as your boyfriend would have definitely told you, a jealous, 'psycho ex' who was trying to ruin his life?

I also think that, even if she took your message seriously, she would confront him about it and tell him who it was that had messaged her. Given that you know your ex has dangerous tendencies towards controlling, narcissistic behaviour, I think you should definitely consider how he might react to that and whether he might try to find you or contact you. I think I would be inclined to avoid doing anything that might bring this man back into contact with you in any way.

I also think your friends really, really need to stop bloody giving you updates on his life. It's unhelpful, it rakes up the trauma you suffered again, and it's basically being done to satisfy their need for gossip and drama. Ask them to stop. You don't need to hear anything about him or his life ever again.