If you have sex with any girl who is not a virgin - guess what? You MIGHT get a disease. Even if she has only slept with one other guy you have just slept with every person that person has slept with in addition to all of the partners those people have had.
Yes, the likelihood is reduced, the less times the woman in question has had intercourse but to think that you are "safe" based strictly on numbers, you couldn't be more wrong.
Sex with a condom doesn't feel great for the woman either and can become quite uncomfortable, but considering the risks, I never minded THAT much. I may be old but I want to live as long as I can with the best quality of life that I can. Not using condoms unless you are in a long term monogamous relationship is IMHO foolish.