I ratted a co worker out coming to work drunk. normal i feel no guilt?

My job requires quite a bit of teamwork, and if one person slacks off everyone else has to make up for them. I'm only 18 working as a busboy, its not exactly a complicated job, but its pretty hard work on busy nights. Like the night this happened. Everyone at my work thought me and this kid were buddies. Truthfully I was just hoping he could replace the lazy guy that got fired and he would be a hard worker. But he half assed everything. There are two rooms to the restaurant. 2 busboys in each, 1 switching between to help both rooms out. I told him I'm doing that. He agreed and said ok. When he arrived at work he said he drank blue something. And I could already tell without him telling me, that something was off about him. Many times I saw him wandering around, I went to the other room and the guy in there said hes getting no help from our drunk co worker. So I stayed in there to make up for him. This guy gets mad kinda easily, and the alchohol made it worse. A waitress asked us to do something while we were cleaning a big table, and I was about to ask him which does he want to do, when we hear the waitress yell at us and say she has it. He then stormed out, interrupted my manager while she was busy, complaining about the waitress, and threatening to quit. Me and the other guy were really annoyed and fed up with him, so I told my manager he's drunk. That pretty much ruined his chances of him keeping the job. Later that night he said "She thinks I'm fucking drunk, I'm not. I havent been drinking for the past 6 hours." Our shift lasts 4, so he drank 2 hours before he came in. I wasnt sure what to say to such stupidity, so I just said "Yeah what the fuck man" and walked away. He doesnt even understand why he was fired, he was confused about it. I really felt no guilt telling my manager, and I still dont. Two of my coworkers said I should've just minded my own business and kept working. Should I feel bad?