I recently took an out of state trip with my boyfriend to celebrate his birthday. On the eve of his birthday, a girl called him and he took the call in the bathroom, essentially whispering. When he came out of the bathroom, I asked him who called him, and he said it was his niece. Something felt off about it to me. So when he was sleeping that night, I took his phone and went through the call log. This was the first time I have ever gone through his phone. The call was not from his niece, but from some girl that I didn’t know. I went on his text messages from that girl and found nothing, but on the text messages it said the convo was moved to WhatsApp. So I went on WhatsApp and his chats with this girl was under password. I went on the chats and saw some inappropriate messages; where they were saying good morning to each other in an endearing way, talking about a magical time they had together in March, and also about hugging each other. I am pretty sure I saw more things but I got so freaked out that I don’t remember. My body’s reaction to the news was extreme; I had a full on panic attack and everything rational I knew went out the window. Like for example; I should’ve taken screenshots of these messages. So anyway I freaked out, and woke up my boyfriend in the middle of the night. He yelled at me for going through his phone, and kept questioning me on how I opened his phone. I told him I had his password and the only reason I went through his phone was because I felt an off vibe. He kept telling me how he owes me no explanation since I went through his phone. Afterwards, when I was questioning him; he had a really guilty look on his face and he was silent the entire time. The next morning he tells me that that girl is actually his cousin and that she is getting married next month. I begged him to go through the messages with me so I can have some peace of mind. He refused and told me that this relationship would not work if I don’t trust him. I told him I needed a couple of days to process everything and we should be meeting up soon. I plan on asking him to go through the messages with me when we do meet up. If he refuses, I have made up my mind that I am breaking up with him. My question is am I overreacting or are my concerns valid? Is it an overreaction to break up with him if he doesn’t show me the messages?