I caught my boyfriend on a date with another girl while he thought I was away

So last night my boyfriend told me he had to leave for a few days for a work trip. I live in a different town, we don't live in the same place, so he called me to let me know he was leaving. I was busy studying for my exam today and didn't really pay attention to what he said, I just kinda nodded and said ok, mainly focusing on my own thing. I didn't notice my boyfriend said it wasn't for work, it was for a date with another girl. Later that night, when I should have been in bed already, I decided to check on what he said about his trip because I didn't really hear what he said. So I checked the voice note and was shocked to find out it was a date. He specifically said "Hey, I'm leaving, going on a date with another girl". I immediately called him and was very angry with him. He was clearly drunk and talking weird. He first said he wasn't with another girl but I told him I heard his voice note, and then he said he was very drunk and didn't know what he said. I told him to tell me the truth and he said "I'm with a girl, I'm drunk, you know how it is". I was very annoyed and finished the call, and I just cried for a while. It hurts so much and I feel betrayed. Up until this point, he had always been very caring and helpful towards me, but this just makes me hate him. I don't know how to feel but I do know I'll never trust him again.