<human>: Condense the text into a few key points

I believe I'm in a tight spot right now. I've been been dating my loving girlfriend for about 6 months now, and as soon as we started having sex we got tested for STIs and both of our tests returned clean.

So this last week she went to her gynecologist for a routine check up and the doctor found a wart I guess, prompted her an HPV test and it got back positive.

Well, the thing is: My girlfriend lives with her sister. They share towels, bedsheets, a bathroom toilet and what not. It's known for a fact that her sister had (or still has, I don't know) HPV in the past that she got from an ex-boyfriend of hers; so my girlfriend excuses is that she got it from her. 

So please enlighten me. Is it really possible to catch HPV like that or should I just face the fact that I got cheated on?

I believe it's a stupid question but, are there chances I am not infected?

Thanks in advance
<bot>: GF is tested positive with HPV, says she got it from sharing bedsheets, towels and and bathroom with her HPV positive sister