My boyfriend went through my phone

One night while I was sleeping at my SO house he went through my phone. I had nothing bad except some rants to my bestfriend and mom about some thing he did that pissed me off. He got mad and didn't tell me why. I realized in my pictures there were screen shots of my conversation and I asked him and he finally admitted going through my phone while I was asleep. Do I have the right to be mad? Or should I apologize for my rants.