I know that this is the question I need to be asking myself and have been doing it for the last 2+ m...
Congrats that you reported an abuser. Sorry you are in such despair. Four years ago, I was in similar situation. Personality Disorder of some kind?
Typical Narcissist will live-out relationship in 3 phases: Elevate [luv-bomb]; Devalue [verbal abuse & smear campaign] & Discard. You got rid of him
before he discarded you. Yea!
He is/was User & Abuser. You did the smart thing. If he is a narcissist/sociopath then he likes your pain. Think about that.
It takes right INFO & on-going Support to have your heart & body chemistry catch up with your sound reason. I could NOT understand it either - WHY & HOW could I miss him!? I was confused, angry at him & angry at myself & very, very grieved - anxiety, depression, insomnia, obsessive thinking TRYING to understand
him, the relationship, myself. Discovering narcissism/borderline behavior in relationships was a huge first step to my healing. That ended my confusion & the paralysis of analysis. Then gradually my body chemistry calmed down & my heart slowly mended.
Yep, regular attachment to another & "trauma bond" & withdrawal [like from an addiction] - his narcissism & my codependence. It was not easy or quick. I now know all the signs of personality disorders & will be on the look out for those signs in future relationships. Working on my issues until then. I wish you peace.