I’m turning into the girlfriend (24F) I never wanted to be..

So my boyfriend(M 24) and I have been dating for a year, keep in mind this is someone completely opposite compared to who I’ve dated in the past. Recently I caught him in a lie with this close friend of his. Though they’ve been friends for a long time and I personally met her/never minded her, he lied. He went out with friends and lied about this girl being there even though I asked who all ended up being there. Apparently his exes were skeptical about this girl too but I never was until this incident occurred. His reasoning for lying was because I seemed mad any time her name was mentioned, but during particular day I had something else going on. Following this moment is when I caught him in the lie, so I’m assuming he never planned to tell me she was there. Long story short, since this occurrence my trust for him has been hard.

In the past I’ve been cheated on three times, so of course my first assumption is cheating. He had done all that’s possible to assure me that he’s not cheating..but here I am being skeptical. I know this is wrong, but I went through his phone. After this incident happened, due to my paranoia of him cheating on me with this girl, he said that he told her to stop talking to him. Apparently he texted her this. Before going through his phone I asked him exactly what he said to her as a way of seeing if he’d show me their messages. Since he didn’t I waited to see if he’d tell me, he didn’t and that’s why I went through his phone. There were messages with them two beforehand but after him telling me of cutting things off with her, their messages weren’t on his phone. I know this is extremely wrong and a relationship shouldn’t be like this however, when you’ve been through something like this multiple times then clearly my first thought is thus. I’ve never felt like I had to go through anyone’s phone (even after being cheated on the second time), but this just had me paranoid. Any time her name is mentioned, he gets defensive. It’s not like I can tell him “hey I went through your phone.” I’m asking for any advice/personal experience related to this because I’m not too fond of this feeling and making these decisions. In my opinion, a relationship shouldn’t be like this and I’m unsure of how to trust him or move past it..