Boyfriend problems

Hey guys so I’m 20 years old, boyfriend is 24, So yesterday I was with my him, we’ve been together 10 months, and I know it was wrong but I went through his phone while he was asleep, and he had deactivated his Facebook and his Instagram, but I noticed he had logged into a different Facebook account, I believe it was like an old one, had no picture or anything, and didn’t have any friends or conversations with anybody. Anyways, so a while ago we had gotten in a fight because he was looking up a bunch of girls on Facebook and on twitter and stuff, so then yesterday I saw that he searched up this one girl he used to date before me. He has known this girl since they were little and they were on and off. They were never “official” but they dated. And from what I know, he hasn’t even talked to her at all from the time that we’ve been together. He deleted her number and social media, but yesterday he looked her up on Facebook. So I broke up with him 😢 I asked him why he looked her up and he said “no reason, I just thought to but it didn’t mean anything” and then I asked him if he still had feelings for her and first he said “not really” but I think he said that because he looked super nervous, and then he said “not at all”. But idk.. was I wrong?