Help New relationship

I had a 4year relationship broke up and it caused me a lot of trauma to be honest. I am now with. Loving guy he has also had a past (my ex didn’t)

But I find myself if something slightly happens in this new one no matter how big or small my guard completely goes up and I’m like in my head “ik how this ends xyz” like that I overthink. What do I do obviously we are only going out 3 months and he’s going to learn the ways I like to be loved vise versa and figure out what we do and don’t stand for but I’m so like Thrown by one small thing and I know it’s because of my past. How do I help this? Any advice? What would you do

He is sm better than my ex I now wear the skirt and not the pants