my boyfriend goes through my phone..

Monica • My best qualities I have is: I can nap, I like to watch Netflix for long periods of time, and I like makeup(:
My boyfriend has decided recently that he's going to go through my phone. I have no problem with that except he did it while I was sleeping. I've told him several time he can go through my phone and put his thumb print in my phone. 
But now it's become a HUGE issue. He goes through my texts between my best friend from back home and I's conversation. He'll nip pick point where he feels I did something wrong. Or I shouldn't complain to her first about him. So now I don't want to delete my texts. I don't have an issue all the time it's small things. And you know sometimes you may just want to talk to someone else who's been in years of relationships and ask advice. 
What should I do?
**Disclaimer: I'm not gonna make an excuse but he does have MAJOR trust issue because of what a parent did to another parent when he was younger. So I have been patient but I told him if he wants to go through do it while I'm awake. He has and he still nit picks.**