Fucked my roomates girlfriend

Ok I feel terrible for this (kinda) but the question is does this make a bad person? So my roommate and his girlfriend broke up but she still lived with us so we planned on day drinking and cleaning the house and going to get food, cut too were drinking and she started telling me how he never goes down on her this that and the other and in my drunk mind I'm just like bet.. So conversation goes on and I make a bet I could get her off in under 5 minutes by going down on her, cut too again and in eating her out, after 3 or 4 minutes she's basically begging for me to fuck her and of course at that point in going too. Duh.. But I came in her and she went later that night and had sex with my roommate with my cum inside her then 2 days later they were back together, does this make me a shitty person??