Trust issues

So a couple weeks ago, my boyfriend went to my apartment while I was out of town to "borrow some movies." While there he took it upon himself to go through the messages on my old phone (I got a new one about a month or two before this). He found some texts between me and another guy. Long story short, I had still been texting someone when me and my bf first got together because I was very unsure about the relationship. After a couple weeks, I was no longer doubting the relationship and I started to really fall for him. I stopped texting with the other guy and eventually blocked him and deleted the number (and let's be clear, it was just texting).

So he found the messages and called me out on them. We decided not to break up and he gave me a second chance because the texting happened at the very beginning of the relationship and I cut it off when we started having real feelings. Anyways, he still says I cheated on him and any time I use my phone he gets upset and freaks out thinking I'm "cheating" again. Tonight I said I was going out with a female friend from work and I asked him if he wanted to go too. He said no. But then he got upset and said he doesn't know for sure who I'm going out with tonight and it could be a guy. I freakin asked him to go too... why would I do that if I was planning on cheating?? I tried asking him that, but he was already mad and just got off the phone. We are so great together and I love him so much... but lately, he's acting like everything I do now is suspicious and it's all my fault that he can't trust anything I say anymore. I think he's over reacting. Did I fuck up in the beginning by continuing to text someone longer than I should have? Yes. But I didn't cheat and I think he's treating me unfairly.

Any opinions?