Someone help need real advice bad?

Well about 7 months ago i was invited to a party and the host gave me some xanex and i was drinking and got real messed up and ended up skrewing this girl and somehow ended up on their roof well turn out the girl was the hosts wife while he was passed out later my friends told me the storie because i did not even remember anything until i was told .about it well the girl is about 7 months pregnant and am told it may be mine sould i wait until the child is born or should i tell dude that his kid might be mine.If it is mine i want to know so i can be there.I feel really bad for it but i was not aware that she was with anyone at the time . I know if i tell him there will be fist flyin but thats not the point any good advice i would apricate couse i dont want to leave the girl in the dark.But how would i know if its mine unless i tell dude.I could not let another man take care of my child.But if it is not i feel i just ruined their life please help
the host is not my friend the girl i met that night i just have a conscience and would not want my girl to cheat on me