Is this considderd cheating?

I went to a Party a few days ago at my friends house. I had been drinking ALOT and today the girl who had invited me admitted to touching my and sucking it. I dont remembre having this hallen at all. I thinking i wad ped out. Im gong to tell my girlfriend because i want to be honesto but would she thinking i curares on her? I did not wonet anybody to touch me there and. I didnt have any intintions of cheating.