Can I be mad?

So I know it was wrong, but I went through my boyfriend’s phone. I found that when he went out with his friends the other night, he had dm’d a girl he used to kind of date. They apparently ran into each other leaving and entering one bar and he dm’d her to tell her “my friends forced me to leave” and then told her where they were going. We’ve been together for 2 years and I’m honestly pretty upset. Should I bring it up or am I in the wrong for going through his phone?