Is he just being Manipulative?

This morning I went through my boyfriend’s phone and saw messages between him and another woman. For the past two days I asked him has he beeen talking to anyone because he comes home a little late from work everyday. He told me no I kind of believed him but I still had this gut feeling. I went in his phone and saw messages and confronted him. He had nothing to say so I went in the other room crying because I just feel like an idiot. He came in the other room and asked for my phone password, I told him no and to leave me alone also ok for a fact he knows my password Because he had my phone the other day. He then says because I’ve been cheating and hiding things 😕. When honestly I haven’t. I would’ve gave him the password with no problem but I only said no because I felt like he’s just trying to find a way to flip things on me…