What steps should I take if my boyfriend is accessing all my passwords without my permission?

My boyfriend, who is 23, and I, at 21, have been together for about a year. Things were going well until recently when we started experiencing some petty arguments and disagreements. He has revealed that he has been cheated on in the past, and my tendency to be closed off at times doesn’t help the situation. It hasn’t helped that he’s seen the numerous messages and likes I receive on Facebook whenever I post a picture. It began with small things, like him going through my past FaceTime logs and texting unfamiliar numbers, asking whether they’d been in contact with me since we started dating. That was really embarrassing. We talked it over and decided to focus on building more trust. However, I discovered that he has somehow gained access to all my social media accounts. I found this out because he knows specific details about whom I’ve accepted or blocked. Upon checking my settings, I noticed logins from his device and location. I feel vulnerable and that my privacy has been completely violated, and I’m unsure how to handle this situation.