Should I Contact The Girl?

Okay. So, first thing that needs to be known is I broke up with an abusive boyfriend about two years ago. It was messy and rough, and he still to this day tries to contact me. He stalked me and harassed me for the first year. Im in a new relationship now, and so is he.

The problem I'm having, is that I am a live cam model and porn actress lol. I started this after the break up, and now I have proof of my ex watching my live streams and tipping me. Normally, id think hell Yeah! Give me your money lmao. But this guy is not safe and I feel for the girl he's with, she is much younger than us and very sweet and innocent, I was her friend for awhile and know she was the type to save sex and all for someone she trusted and loved. I don't want her to be hurt by him, and so it's make since for her to not know... But I also dated the guy for 5 years and he was always doing something fishy and not knowing killed me. I'd want to know if my boyfriend was doing this, but I'm conflicted about showing her the truth because he of course bad mouthed me when they met and made her and all her friends turn against me. Im worried about coming off like a stalker or jealous, but I couldn't care less about my exes new flings, I just don't want this girl to get hurt or look dumb. I also have messages of him saying how hot her friend is and how he'd rather sleep with her friend.. I just want this girl to get out before it's too late!

Should I show her? My boyfriend thinks I should use the proof as blackmail but this girl is literally the most genuine and nice person I have ever met