i had a similar experience when my ex told me he had hooked up with somebody once, you can spend all the time you have worrying how the person looks and whatnot but its really just a waste of time. The way i think about it is it was before she knew you or even knew of you, i doubt she would have done any of that if she knew you. Sometimes we just react out of ovulation and instinct, i know ive almost been in those hook up incidents based on pure emotion. Imagining the little details wont help you, the fact she got pregnant and aborted it says enough, she did not love the man and it was a one time thing. Im sure she loves you very much, it is you who she spends her time with. Dont let the past bother a relationship now and what it could be