I dated a NVM in my early 20s (I'm 30 now) who was verbally abusive and even ended up hitting me after only a year of dating. I was a severe pickme throughout my 20s and I continued dating him for another year before breaking up. I obviously did not deserve it, but I had extremely low self worth.

A little over 5 years ago while still very much in my pickme stage, I reconnected with my ex and we ended up spending a weekend away together. We went to a party at his friend's house and there were a bunch of his friends there who I knew from when we previously dated. Throughout the weekend we slept together a few times and then went our separate ways at the end of the weekend, keeping loosely in touch as "friends" over the next several months.

Less than a year after we reconnected, I ended up finding out that he had a girlfriend at the time we hooked up and spent the weekend together. I found her IG account through a comment she left on one of his IG posts, her account was public and it appeared they had been dating for awhile and still together based on the pictures.. like at least a year beforehand. His friends obviously must have known they were dating too, so that was a super shitty realization too.

I was debating on what to do with this information and it seemed like his douche spidey sense went off or something, because within days of me finding all this out, he ended up sending me this long ass email seemingly out of nowhere, where he admitted to cheating on his gf with me and BLAMED IT ON ME. He even went on to say how he "wasted years of his life on me" and told me to not even bother replying because he was blocking me on everything.

To this day he still has me blocked which is good, I never want to speak to his disgusting ass ever again and I'm pretty sure he's a sociopath. I do however carry guilt about not sharing his behaviour with his gf who seems like a genuinely good person. Over the past few years I have thought about sending his gf a message with screenshots to let her know what happened. They are still together.. I don't think about this often but it pops in my mind from time to time. The thing is it's been 5 years now and I feel like I should have said something long ago if I was going to say anything to her at all. I don't want to cause drama, she seems genuinely happy with him, on the other hand she also seems very successful and surely deserves and would want to know what a depraved piece of shit he is so that she can continue to excel in life without him. I know I would. Or maybe she already knows about it, but I doubt it.

What would you do?