I (20f) found out my (21m) boyfriend lied to me about where he was, but I found out by snooping. What should I do?

We have been together for about a year and always hang out together when we have free time. A couple of weeks ago we attended a LAN (gaming) party with a couple of of our friends where we had lots of fun playing a card game called magic the gathering. Neither of us had played before and he was really exited to play it, but I was a little nervous about how difficult it would be and didn't understand a some of the mechanics. Even so, I liked it a lot and expressed that I had fun. Afterwards its all he talked about for days, telling me about new cards he had looked up and new deck ideas he had or ideas for decks I should try, I always told him how cool they were. The last time I heard of it was the middle of last week, he told me that his friend hosts a tournament at his house every week and we should go sometime. I told him that would be great!

Then he went silent on the topic, I haven't heard about it since. After that he has been busy a few times when we used to hang out and seemed kind of evasive about where he was, not texting me at all while he was gone. I didn't pry but I got suspicious and joined a chat server I know he messages in last night (he doesn't know I joined) where I found that had been talking about it a lot with his online friends. That's fine he doesn't have to tell me what he talks about with his friends, but there was one specific instance where he said that he was about to go play magic the gathering at his local game store again right then (I didn't even know he did this once). I checked my texts and found that minutes before that he told me he was going to come to my place, but he didn't show for almost 3 hours. He had kept messaging me saying he would come over in a bit, I was patient with him because I figured he was just busy or something. He came up with some unprompted excuses about how he was just going to finish watching this tv show / youtube video then be right there. I thought it was suspicious and unlike him at the time but had no reason to not trust him.

Now I don't know what to think about it, I don't care that he wanted to play more of the game without me, but I really care that he has been lying/misleading me about it. Now I have been thinking about it a lot and its got into my head, its become hard to trust him about where he is going. I have been thinking about what else he could be lying about, if something like this that I barely care about is worth it, what else is going on? is there something bigger that has made him comfortable lying to me? It has me scared for our relationship. Now here is the thing, something similar to this happened before a few months ago and I joined the same chat to find out what was going on with him. He noticed I joined that time and got really angry about me invading his space which scared me and I left it alone. I am scared to bring it up to him because I know he wont react well to me doing that again and I am really bad at confrontation. Am I just overreacting? Can anyone give me any advice on how I should deal with this situation? Thank you.

*TL;DR - My boyfriend has been lying about what he is doing, and I'm scared to tell him I know because I found out while reading his messages to someone else.