Sorry he’s put you in this position. Although I understand you want to warn her often the messenger is the one who cops it, plus they’re not always listened to particularly if they could be seen to have a hidden agenda and you know this first hand because you ignored the warning some other woman tried to give you.I don’t want to stress her out. At all. Woman to woman though. No?! I had messages from an ex of his when I was 5 months pregnant predicting what he would do. I wish I’d taken heed. Bloody head so he is.
He seems a nasty piece of work from what you’ve said, and possibly emotionally manipulative - he’ll find a way to get out of it and make it your fault and she might want to believe him because she’s pregnant and she loves him.
I think your response was the right one. You are not responsible for his actions, or preventing other people from being hurt by them.