I Got A Girl Pregnant And Not Sure How To Handle It?

At a party she got drunk and kept hitting and rubbing on me all night so I finally took her to a bedroom and just did her bare without condom. She started dating my friend a few days later. I guess she does not remember what we did at the party and believes the father is her boyfriend, but its mine. Should I tell her or just let it go? I am kinda feeling bad about it but she might never let me see the kid cuz she thinks I am kind of a jock snob? I could not tell her and let my friend handle it with her? It is complicated im 19 so need your help.