<human>: Summarize the given text in a few sentences.

Just to preface, we've been dating for a year and its been an amazing year.  She has always been extremely faithful and open and I know she never would want to do this. 

She was at a party on Friday that one of her co-workers [m] invited her to.  Apparently she got too drunk and ended up throwing up.  The coworker she went with helped her while she was sick, but then they went to bed. Apparently they were just talking for a while and then they kissed and then one thing led to another, they had sex for "literally a second" before she freaked out and couldnt do it.  

She called me the next morning sobbing.  I really want to believe her story and forgive her but I've been cheated on before and it was a terrible experience that set me back for a year or two emotionally.  I really do love this girl but I just can't believe that this is happening. I feel so blindsided.  Do I try to work through this?  How can I try?
<bot>: gf of a year had sex for a split second with another guy while blackout at a party, immediately confessed, now I don't know what to do