Actually getting cervical cancer from HPV is not all that common - so she is a very unlucky lady.
If she has not had a second opinion I highly recommend it as as the consequences at her age are pretty bad. Dependent upon a number of factors she may have to have a complete hysterectomy - which would mean she cannot give birth to children.
After she is treated she will most likely go thru premature menopause. Dependent upon the treatment her vagina will get smaller and dryer. She may experience pain with sex if radiation is used.
Most everyone gets HPV these days eventually. How much of guarantee you want will depend on your behavior. You are at no greater risk for prostate cancer. But if YOU get HPV there may be women who do not want to have sex with you.
To protect yourself you need to use condoms for anal, AND vaginal sex with her. You need to use dental damn for oral sex on her. This isn't perfect protection - but then there isn't any better.
You also need to use a good quality lubrication. See my webpage for the stuff I think is best.
http://www.sexsupport.org/toys.html
This is so sad. If you decide you do not want to have sex with her (which is a reasonable, but not your only right choice) I hope you can find a way to be close and loving.
Susan