LADIES!! Why am I like this...

So ladies I know I’m wrong for this but drop your options!

So my boyfriend has this coworker that I cannot stand!! Well we were laying down watching tv and I left to use them restroom. As I was coming back I saw him texting and once I laid back down I saw him quickly exiting out the text message and went on Instagram

I didn’t say anything but then he left the room and saw a new message. I told him who it was and he said it’s the girl coworker I didn’t like. So I told him what did she say. He said it had to do something with work so I told him why did he exited out the messages real quick and he was bullshitting acting like he didn’t. I legit told him to let me see the messages and he did and sure enough it was about work

I felt so stupid and he was extremely mad at me ( I don’t blame him ) I just hate having trust issues and don’t know how to over come then. He did not speak to me the whole day and I felt like he shouldn’t have got that mad due to him exiting out the messages so quickly and hiding it! Am I wrong to ask to see the messages? Should he have got that upset with me?