First of all, was her throat cancer caused by HPV? If it was caused by smoking, for example, it would not put you at risk.
Second, here is from another website (Web MD) about research showing that someone whose throat cancer did come from HPV is not likely to spread it to his or her kissing partners.
"Spouses and long-term partners of patients with HPV-related oral cancers appear to have no increased risk of oral HPV infections, according to the results of a new study led by Johns Hopkins investigators.
"Saliva samples taken from the partners of oral cancer patients did not contain elevated levels of HPV DNA, the researchers reported online April 28 in the Journal of Clinical Oncology."
You could look up the Johns Hopkins research or that issue of the Journal of Clinical Oncology for more information.