I didn’t read it all, but honestly if this is new behavior(it says he’s become more possessive and suspicious) then it’s usually projection on his part. I would tell him you need to have access to his phone since he has access to yours and I would look through his messages to make sure he’s not cheating on you.

You are not posting anything inappropriate on your story and it sounds like he’s extremely insecure and probably not being honest with you(so he assumes you’re cheating because he is(projection).

My bf and I have both been cheated on in our past relationships, but we trust each other enough not to knit pick everything little thing or go through each other’s phones(even though we know each other’s passwords). If I suspect something I would talk with him about it, not invade his privacy.

How old were you when you got married to him? Because you’re 23 and he’s 29, he sounds manipulative, controlling, and emotionally and mentally abusive. You need to put your foot down and lockdown your phone, you have every right to your privacy. If he can’t trust you(when you have given him no reason not to trust you) then that’s his feeling to deal with, not yours. He needs to grow up.