What the fuck just happened??

So me and some guy from work are shagging and it was quite good. Then my phone pings and he goes "ha, that'll be Pete" so I'm like "eh why?" (Pete's just some guy I know from work) and he's like "well you're shagging him aren't you?" And I'm like "no... Pete has a girlfriend!" And as I'm saying that he thrusts hard and cums in me and rubs my clit so I cum just as he says "so what... I do too!"

Like what?!?!? You have a girlfriend?!? I just cummed all over you and fucked you so you had a good orgasm and you have a fucking girlfriend??

Like that was good sex but what the hell am I supposed to do now?? I feel so gross and feel like a homewrecker!