Well OP from all our outsiders perspectives this was an obvious outcome. He clearly had one foot out the door of the rl he was halfheartedly in with you and and fully in hers, sorry but no man is so invested with a child of a short term ex like her w/o being obsessed with her.
Sorry to say you were a rebound that he treated poorly.
All you can do now is reflect on your part in this while you recuperate. Get into therapy if you can (if that’s a no go then very least make several posts here so you can understand and process why you let this happen)
-Explore why you accepted him treating you “less than”.
-Figure out why you are/were painting this 6 month! situationship as far bigger than was in reality. You were neither of you “so in love”. He was clearly using you as a halfhearted rebound, but you equally did not actually love him, codependent, limerant, desperate for something (validation?) yes but in true love you were not. True love is comfortable, trust, security, can you say you truly felt those with him? How was your relationships with your parents?
-You need to reflect on how your brain has labelled and talked about your ex and then his ex. Maybe read this thread back again in a few weeks so you can hopefully see how you’ve tried to put him on a pedestal while simultaneously being quick to disparaging her here (and probably IRL),, happy to demonise her on only his untrustworthy word (“she got pregnant sleeping with a dealer”, “he said her breath stank and she was shit in bed” etc, eagerly relaying the nasty venomous things ex had said about her,… this hopefully will be a lesson learned that a male who talks disgustingly offensively about a woman, would be with her in a heartbeat more often than not, and this is a reason to run to the hills, not think you’re his forever nor want him as yours
)
You’ve lapped up this bile as you are clearly incredibly insecure (for good reason wrt him) and wanted to believe she was a bad gross immoral thing and you were special and the one. You learned an important lesson that a man who describes his ex in horrible ways, is the massive red flag, not her. See also “my ex is a crazy bitch”.
Finally, I am glad to read your update. Not because I want you to be hurt, which you inevitably are, but because this weak excuse of a male already had you exactly where he wanted you; insecure, anxious, hurt confused and doing the “pick me dance (google pick me + Chumplady and see how common this is)
,competing with another woman for the sole reason of boosting his pathetic ego.
i know it hurts very badly right now, and i hope my post doesn’t come across as harsh, i am speaking ten years out from recovering from the pain of not one, but two narcissistic, cruel relationships like him, strung along, pitted against other women, who were never the problem, and after you give yourself a few days to lick your wounds I really hope you spend those days reading up on Chumplady, whose been helping women for decades now, and here, make a new post if need be, you’ll get support, anywhere you can read with other real women who’ve gone thru this, any and all “oh shit, it’s not me, these cunts are pros at this shit” that can help you realise you’re not alone, and give you all the preparation so you find self respect and never fall into this situation again.
All the best OP