In love with his best mate!

Basically, I have known this guy for about a year and since the first time I met him havent been able to stop thinking about him. I rarely like anyone and he is my idea of perfection...he has no idea i feel this way though and he now has a girlfriend.
Anyway a few months after knowing him I met one of his other friends whilst out, we became very good friends and would meet up quite a lot just us two but i had no feelings for him, i didnt think he did either until he confessed to me the other month that he was in love with me and even though i told him i only wanted to be friends, i stupidly and drunkenly kissed him, immediately regretted it :/

so yeah i dunno nwhat to do, cause i dont know if i should hold out for this other guy cause i have had like definite signals he feels the same way, but even if he wasnt with his gf i dont know if he would choose his friends loyalty... i have turned down people who have asked me out all year cause noone seems to live up to him but maybe i should jsut get over it?