Heartbreak, trust issues and opening up to someone.

I was in a 1 year relationship, which ended poorly. My ex would gaslight me and ignore me when I needed his attention. We ended, and well after that I wasn't the same. I became very self destructive, doing things that weren't normal for me. And I spent two years up to now trying to find someone to feel validated, and would end up getting my feelings hurts cause of it. Just people leading me on. So here I am, testing the waters with someone. And this person treats me differently to what I'm used to. And I can't open up to this person because of past relationships, and he knows this. He has been so patient with me but I'm scared of our relationship because if I open up he might leave me or hate me. So any advice of how to move past this? Because I'm tired of the insecurity I have over the relationship. I'm tired feeling the way I do. I want to tell him everything but I don't know how, like I want to open my heart up but I'm at a loss for it. I want to begin to trust him, and I want to be able to finally let go.