Am I crazy for bringing it up again? (long)

Early in our relationship, me and my boyfriend talked about our previous relationships and he confessed that he has cheated a couple of times and that he has a history of being disloyal. I don’t know why I didn’t bother with that information, but I don’t believe that once a cheater always a cheater. People change and I wanted to give him the benefit of the doubt. I have always been careful with him since I was cheated on in my last relationship. He was messaging girls behind my back and lied to my face about it. A while ago, in April, my boyfriend got a new female colleague. They hit it off together and befriended each other on social media. Because of my “trust issues” from the past I was kind of suspicious because he talked about her a lot, more than he did with his other colleagues. I had a bad dream about it, went through his phone and uncovered deleted texts between them. There were nothing flirty or sexual, but he was definitely interested in talking to her and getting to know her, and it seemed like he wanted to be funny and impress her. He was telling her about his family and siblings, and he was texting her after work hours before bed (while I wasn’t there with him). When I confronted him he said that the texts were casual, not flirty, and that I could see them for myself. He said that nothing was going on between them and that he deleted them because he knew i’d be mad, he knew that they had been talking to much and that I would not be happy about it, so he hid it from me. We haven’t talked about it since then, but it has always been on my mind because it still bothers me. I would have never done that, it was inappropriate for a taken man to be acting like that. However, recently that situation reminded me of something my boyfriend told me about early in our relationship. In his last relationship his ex discovered that he had downloaded tinder. He was messaging girls, but it was nothing sexual or romantic. He didn’t want to meet up with them, he just wanted to chat casual with them. Just like he did with his colleague. I know that his intentioned with his female colleague was not clean/ pure because why would he hide it from me. I wouldn’t have been upset if there was nothing to be upset about, and he knew it too. Those situations seem similar to me, how he talks to the women and how it’s painted as nothing bad because he’s not flirting with them. But he is entertaining them and breaking boundaries for what’s okay in a relationship. Would I be wrong for bringing this up again? I can’t seem to get over it, I don’t know why or what to do