Seems good that he is old news for you, whether paranoia or instinct he is gone. It is possible he has traits of a psychopath. They have no social conscience and rarely a personal one, and they blame others for their own problems, particularly their victims

They can mingle well because being social predators they will hone in on a target and charm them, however they would give nothing away and be the "perfect" personality in order to achieve their aims or desires.

Killers will not show their hand and not to anyone and if they think they have, they will kill the one who could point the finger at them. But this is a tiny tiny sliver of a look through a broken window at the psychopath or sociopathic personality

Whatever the reason you are probably very lucky to be without him