Take your focus off him. Put focus on yourself.

Don’t ask why he did this or that. Ask yourself why you took on an unemployed addict whom you barely knew snd why did you stay with him after he stole from you etc etc and how to make sure it never happens again.

Truly focus on that with your therapist. When you start working on that then you’ll heal and it will not be important why he did things.

When something bad happens to me I try to understand what’s my role in it? Why did I allow that? What can I change in me so it never happens again? Then you’ll heal faster because you are in charge of your own life (including your own bad choices) rather than a victim of someone’s bad treatment and someone else’s choices.

And count your blessings. You only spent few months face to face with this man. Didn’t marry, lived 30 years, had kids etc and then found he had a second family or something (happens to people). It has not been long term relationship so be glad you got out early

PS I do understand how you feel of course. It’s painful.