I NEED ADVICE!

So about 2 months ago I went up to visit my bff in college and we went to this frat party. During this frat party I was eyeing this guy but everyone told me to stay away from him because he has a girlfriend. I respected that and I left him alone. Later that night he came up to me and started to flirt with me. Me being confused I left to go talk with my friend. I asked her “why is he flirting with me? I thought oh said he had a gf?” She later goes up to him and asks him he said “no I do not have a gf”. And I had a few of his frat brothers ask if he had a gf and he also said no to them. I took that and we started flirting throughout the night and then finally he invited me up to his room. We ended up talking for a long time and then I personally asked him if he had a girlfriend he also said no to my face. We did not have sex but he ended up going down on me. He felt nervous almost like he wasn’t supposed to be doing this. So the night ends and a few weeks later I FIND OUT HE WAS LYING TO ME! HE DOES HAVE A GIRLFRIEND! I was so pissed off when I found out and I felt terrible for the girl!! So two months later to today.. I get a text from that dude gf asking about what happened that night and I told her everything. I just feel like a shitty person and I am asking for advice if I did anything wrong???

UPDATE!!!!!

So I just found out that the dudes girlfriend is believing him that he didn’t do anything with me. That lying piece of shit!! I feel so bad for the girl but she needs to open her damn eyes and see that she doesn’t deserve him!! But also it’s her life and I tried to tell her. I don’t really care that much because 1. I don’t go to that college and 2.Its not my life.. she can figure out her own problems. Also I’m going back up to visit my friend up at her college again in March. Let’s see what happens when/if I see her and/or I see her bf. Who knows 🤷🏻‍♀️