i cheated on my fiancé last night

so i fucked this guy at the coffee shop, just as we were closing. he came in asking for cream and sugar but also for a quickie behind the counter. i couldn’t resist his charm and hard-on. we had barely finished our shift when i led him to the back room. there was so much cum on my face and hands by the end of it, everyone would have known what happened if they walked in. feels really wrong but also kinda right. am i a terrible person? is this normal for someone who’s engaged?