My bf had this girl friend that I used to be friends with but not anymore because she was too conceited

and just liked getting drunk all the time. I one day found her messaging him late at night asking him to come to her place and bring drinks even though she had a bf at that time. I don't like snooping but the more I read the more I noticed she was always texting him during the times she was drunk and out of booze.. It got me thinking that he really likes this chick enough to not notice she just had him at her disposal. I tried to tell him several times she was just using him (he was the one that had to buy the booze before seeing her). I think he finally realized it after another one of her drunken late night texts and apologized to me but I was feeling bad all those months before.