BF cheated before we even broke up?

So, back in April of last year me and my boyfriend broke up for a couple days and then got back together. He told me during the period we weren’t together he didn’t sleep with anyone or talk to anyone. Fast forward to a couple months ago, he told me that he had in fact been on a dating site the day after we broke up. I was hurt but I got past it and we were doing very well. So the other night I was playing around on his phone ( we are both very open to going through each other’s phone as both of us have nothing to hide.) anyways I managed to find out that he had actually downloaded a hookup app 6 days BEFORE we broke up. Thinking back to the tone period he was always on his phone. He’d let his phone die which he never does and he’d keep his phone in his jean pocket in the floor. Barely touched me or acknowledged me. To make the story short. I ended up signing into the account. Although there were no messages because the app had been deleted... his profile said single. Which is perfectly normal. I dismissed it. But what really bugged me is the profile was made for seeking discreet hookups. I’ve been down ever since. I ended up confronting him about it and he turned it on me saying. Well how do you know that’s the date we broke up. The dates must be wrong because I didn’t download them until we broke up. He didn’t say anything other then that. Shut the conversation down within a minute. He was also quite aggressive about from the beginning of the conversation. What are your guys opinions on the matter?’