Well that is still a risk. Many people with HIV do not know they are infected. It IS unlikely that a) She has it and B) you'll get infected by a one-time exposure.
However, you do still need to test at 3 months post-exposure. The odds are in your favor.
i had unprotected sex with a friend of mine but she said she did not have HIV
What? No.
Use boxers instead of briefs. They're a lot airier.
Have you actually had a risk? Or did you notice sweaty balls and think it was HIV?