Life ruined, huh? I disagree.
Let's say you find some literature or someone tells you the answers to all your questions. Will your OCD go away? I bet you a million bucks it won't.
I often wondered would my OCD go away if I actually got HIV. Ever think about that? I think mine would, but I'm not sure. Anyway, it's about your brain thinking your in danger 24/7. It's not about HIV. If this was the 1920's, we'd be all jacked up about polio or something. I've had OCD for so long, the whole HIV thing is old hat for me.
All I can say is I take about 15g of inositol a day, and I spent 3 months doing CBT. Now, I rarely get fear spikes, my hands are normal looking, and I don't have to buy cleaning products every other day. Everybody has their own flavor of ocd, but I recommend inositol and CBT.
Telling her to trust the doctor when he is saying they don't know if it is contracted enviromentally is not helpful to the situation, I think you meant the other way around, right? Anyways, HIV is blood to blood direct contact. It cannot be contracted enviromentally. SO if you have a cut that is bleeding and someone else also has a bleeding cut and you touch those two cuts together or are letting someone drip blood into your cut, then yes, there's a chance you're going to become infected.
Your OCD is ruling your life just like mine is at this time too. Do not read everything on the net it will fry your brain and even make you more scared. Maybe the best way to work on your OCD about HIV is to face it is to get educated in it, learn how it is transmitted and how it is not.