AIO Is my girlfriend cheating?

So, I’m M(24). My girlfriend is F(28). We are in a long-distance relationship, and we sleep call every night. As soon as I get home from work, we call, and we haven’t missed a day or a night. I play on my PC with her sometimes. Recently, we were playing together, and she decided to get drunk. Around midnight, she got a little bit upset at me because I wasn’t talking to her a lot. I wasn’t talking to her a lot because she was laughing and playing with other people while I was there and just talking to them.

She tells me she’s going out to get more alcohol and that she was going to the store. She lives in Toronto, Canada, so I said, 'OK,' and I waited. But it turns out she went to the bar and was there until two in the morning. I texted her, 'Hey, I wish you would have told me you were going to the bar instead of the store.' Keep in mind, she’s already super drunk and alone. She got upset because I texted her that, then comes home around 2 AM and starts to tell me there was a guy alone at the bar who looked really sad, so she was talking to him. Then, she proceeds to tell me, 'This guy was a weirdo. He called me cute, and I told him I have a boyfriend, but he kept insisting to go to her place.'

So then, after my girlfriend told me that, she hung up the phone and called me back at 3:30 AM. When I try to talk to her about it, she keeps just saying everything is OK and gets mad at me and really defensive. This is not the first time when I think she’s being unfaithful. She always gets really defensive and mad. Keep in mind, she has been cheated on before, and it caused her a lot of trauma and a lot of pain. She told me one time, 'How could I even think she’s cheating when she got cheated on?' and said she would never cause that kind of pain to anyone, but I just don’t know.

Then, when we were on call, I was just being really quiet, wasn’t saying much, and she kept saying, 'I really like you. I really miss you.' Usually, that’s me saying that type of stuff. She kept asking me what was wrong, but I just didn’t say that this is bothering me because she always gets upset and angry, really defensive, but I think she knows. She went to the store yesterday as well, but this time she left her phone on and went to the store, I guess, with me, so to say, while I was on the phone.

I don’t know if I’m honestly just tripping out. I just don’t know what to think anymore. Even when she went to the store, it’s so strange. It sounded like her phone was just standing still, and there were two guys in the background, sort of far away, asking, 'Can I get your snack?' It didn’t sound like she was walking or anything. I think I might just be overthinking everything a lot. I’m honestly really scared. I don’t know what to think, and I don’t know what to do. Please help.