been reading this post for over an hr lol
he sounds exactly like my spermdonor ex.
he too used the 'if you dont shut up, ill dump you' card. he dumped me a number of times, then came back with his tail between his legs. the first few times i fell for it, accepted fault and took him back. but gradually, from the humiliation, i stopped caring.
we split up 7 months ago when he texted me saying 'well i guess its over then bye' and instead of begging him, i said bye back. a week later he was sending me flowers 
6 weeks later and back to his old tricks he tried doing it again. he chucked a variety of threats at me such as a report to social services and court, and again, the 'ill finish it for good' thing. he said 'so youre going to drive away from me then?' to which i replied 'yea i am actually, ta-ta'. and that was it til a few days later when he turned up at my house begging. 
told him it was over and the relationship was dead. he did call ss but they didnt fall for his lies and its backfired on him. it says alot about their cockiness when they are entitled enough to confidently dangle your relationship in front of your face like a carrot.
the first red flag was that he slagged off his ex-wife, mother of his dc. said she was a psycho, liar etc etc- you know the script. i went through a hideous abusive relationship before him so i knew the tricks. in both men, they said their exes were psychotic. did drugs. child abusers. were restricting contact for 'no reason'. it was like a goddamn stuck record.
and i concur on the contacting friends/family thing. what they are generally after is for you to question yourself, the old 'im telling on you' thing, to humiliate you, drag your name through the dirt. the first thing ex fw would do with a row is get out his crapberry and start tap-tap-tapping away, as if to say 'im gonna text (insert allie) and tell on you. im gonna ruin your reputation' .
and like lundy demonstrates, abusers will immediately seek allies when the shit hits the fan. get as many gullible idiots people on his side as possible to make an army against you. n use them to dig dirt on you, stalk you, upset you, shit stir etc. cos they know its the only control they have left.
stick to your guns. cos looking back and remembering how smug this twunt was, how overconfident, cocky and arrogant he was.... then remembering how you waved buh-bye to that, knocking him off his perch, is such a satisfying feeling 
yeah it means im about to have another baby alone, and itll be tiring, but at least i can walk past that sack of shit in the street, hold my head high thinking 'i beat yo ass at your own games' 
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you did nothing wrong in the first place. all you did, like me, is call his bluff 