*sips bourbon*
Kill her.
There is now ay to know for sure.
Yeah, you could ask, and she could deny it, and be telling the truth.
Or, you could ask, she could deny it and be a filthy liar and you'd eventually find out and destroy yourself with "emotions" and have a terrible life in which you can never keep a stable relationship in a self destructive downward spiral.
Or, you could ask, she could come clean, and you could flip the fuck out and see above.
Or, you could ask, she could come clean, and you could accept that you will always have to worry about herpes.
Or, you could accept that when you are dating someone every attractive girls you see will kind of look like her, to the point that you swear to god she's in a million different places at once.
Or, you could ask, and the horrible memories of what she had to do to pay for tuition and the amount of blow she had to consume to drown the memory will come flooding back and she will go on a rampage.
So, save yourself the nightmare. One of you has to go and you have no better way of handling this.
Kill her, it will remain a mystery, but it won't be one that will haunt you. PLUS, if you kill her, and you stop seeing her face in porn, you'll know you were right to do so!
*sips bourbon, puffs cigar. Closes door.*