The only risks for HIV are to have unprotected vaginal or anal intercourse or to share IV needles to inject drugs. Air inactivates the virus. This is why a condom slip is not a risk. The head of your penis is covered and as long as your urethra is covered, you are not at risk. If you penetrated without a condom, and only you know, that is a risk. It is low at less than 1 percent. But if you had the condo slipped up but still on the tip of your penis, you had no risk.
Only the head needs protection so the condom protected you. hiv is dead in air and it doesn't matter how much dead hiv was on the condom sticking out of her.