I feel really bad and down?

Mistakes in judgement happen to us all. Maybe you were drinking. Maybe despite being told you're good looking, you have a bad opinion of yourself or don't have much experience with girls and the attention she paid to you had you flattered to a point you weren't thinking clearly. Or maybe being a 27 year old virgin had you so pent up you would have put it in anything walking by at that point. Just move on... move on down to the free clinic and get a STD check done. Then move on with your life and find a nice girlfriend that will freak you for free and not steal your car while you're asleep : )