When I was dumped, I finally realized that he was lining me up days after his breakup from a two-year relationship (and possibly was chatting me up on Tinder before it ended). If my partner were doing that, I would’ve liked to know - so I reached out to the girl very nicely and told her that sorry to bother her but I just found out I was a rebound and he possibly was involved with me when they were together still and that I didn’t know and I’m sorry. Wow, she lashed out at me and ran to him and they both ganged up on me instead of solving their own issues. He was mad and cruel at me because now his ex knows he was a lousy unfaithful man.
Honestly, and I know this is easier said than done, but you need to stop getting involved with this man and his ex-girlfriends.
I understand that perhaps you wanted someone to sympathise with you over the fact he is a total shit but not everyone wants to know that their ex may have cheated on them behind their back unless they were in danger of going back there. Someone contacting me out of the blue to tell me that may or may not have happened would either make me angry or upset, and I wouldn’t welcome either emotion into my life. I would think the girl telling me was trying to cause trouble for the ex and/or get his attention.
You haven’t mentioned how you know the names and contact details of his exes which also strikes me as odd. If you’re taking time to hunt them down it is more time you are wasting on someone who doesn’t deserve it.
As for this man being angry for you reaching out with your theory, I can see his point of view as it looks like shit stirring.
I can tell from what you’ve written that you’re desperately hurt and upset by his behaviour and rightly so. When I read how he treated you and had the audacity to try and review you my blood boiled on your behalf, but doing anything more that involves this man is only going to prolong the time it takes to move on. Moreover it may see you painted as the ‘psycho ex’ and not believed which will cause you even more pain.
The best way to get back at David is to be happy and leave him for dust. Men like that will never find true happiness because they love themselves more than they could ever love anyone else. Good luck.