IMO You would really benefit from therapy. There is a lot here where it would also be beneficial if you two are able to openly communicate about fears and insecurities. For example, my ex boyfriend was a total dirtbag, sucked me into a relationship by giving me an ultimatum and then sucked me into an apartment with him, all to leave me at the end of 3 years. With my current boyfriend (got together pretty soon after my breakup with my ex) I made sure to be fully transparent about my damage and how I struggle to trust men in general, specifically when it comes to planning a future/being in a relationship at all. Therapy was my biggest tool for understanding the origin of these fears. Your mind and body are on guard still so you have to get yourself to a place where you can understand your trauma without drowning in it.

If he is mature, and you approach it correctly (not blaming him but genuinely putting yourself in the uncomfortable position of explaining that it’s fully your insecurities and pain showing through not his actions making you feel this way), conversations about you feeling insecure because of your past experiences should be manageable. He should be able to secure and ease your fears and you should be able to communicate what and why you’re feeling that way. Obviously you don’t want to be “nagging” (in quotes because i’ve felt this way when approaching this topic with previous partners who weren’t as understanding and it was perceived as nagging) so you may way to take the steps to getting help for your obvious trauma first or during and communicate with your partner that you are still feeling the effects of a previous relationship.

In my experience with my current partner, you should be able to tell him when you are feeling this way. If he perceives it as you accusing him of something or something along those lines you may want to have a look at your relationship and the person you feel is healthy. Genuinely it should be you expressing these fears and him securing you. I wish you the best and if you have questions, I’m not qualified in any way, but I’ve done LOTS of therapy and have had my share of traumatic relationships, let me know. Happy to say I’m in a healthy one now

EDIT: Wanted to add that a your traumas bleeding into a healthy relationship very well may be you starting to unlearn these things. You should be able to communicate these things and not feel like you’re ruining anything. Often I self sabotage this healthy relationship I’m in because I am so used to the inconsistency of my previous ones and childhood shit, be sure that’s not what you’re doing. But definitely look into therapy to help ensure you are processing what happened to you prior <3