I (F22) got leaked that my bf (M24) uses dating apps and it's been ruining our relation ship(F22)

My bf of 3 years(24(m) got into an argument with me (22(f) about how he likes to play video games until about 3-4 am. I'm a good sleeper so I can sleep through the night even when my partner is being awake. I wake up need to use the bathroom. When I was using the bathroom, I saw his phone. When I was looking at his phone, I saw that he was talking to other females and using other apps that we we're not familiar with before. I felt like my world had been shattered. I don't even know what to do. I don't want to bring up the apps or the fact that he was talking to females but I do want to know why he was staying up until 3-4 am. When I asked him why he was staying up this late he said it was because he likes to play video games. This is something that has come up multiple times since we started our relationship. I don't play video games but I've never had a problem with him playing games until now because I feel like it's becoming a problem. When I was looking at his phone I felt like I had been punched in the gut and it's been bothering me for a while now. I haven't brought this up to him but I do want to know what's going on and why is he doing this. Is he still in love with these females or does he not like me anymore. Is there any advice on how to bring this up to him? I'm very scared that when I bring this up he'll leave me or call me crazy or I don't know. I'm very lost right now. Any advice would be helpful.