How to tell him I need him to reme

I had my first panic attack while having sex with one of my exes two years ago because he did something that triggered a flashback and I blacked out... I cried after because it scared me to see him so scared of hurting me. It became the main reason we stopped connecting. I talked to him about my past and we’re friends, since then he’s been my voice of reason whenever I feel worthless... but lately I been feeling worthless and I’m trying so hard not to take it out on the guy I’m in love with. I haven’t told him. I’m afraid of seeing that same look of panic... of knowing how cautious he’d become... I hate that my past is an eternal burden on my love life. I legitimately have someone who cares about me that I can’t touch without remembering who else has been here without my consent. He tells me I deserve things and I always wonder why me? Why did I get to survive? Why did I get to find someone... I don’t know if I can tell him because I don’t know if he’s the one... I hate the thought that if I keep sharing myself there could be an onslaught of people I’ve tried to tell about my past that probably throw it in my face after a breakup. (Yes that’s happen)

Has anyone opened that conversation to a new person before? Do y’all start relationships without telling your partners and wait til you’ve been together a certain amount of time or should I tell him and then see how things work? It’s so conflicting that I can’t decide for myself.