No it is not possible for you to contract HIV from having non-penetrative vaginal sex.
Theoretically? yes, but it is such a miniscule chance you'd have a better chance of winning the lottery 8 times in a row. HIV is a very delicate virus especially when exposed to oxygen like you said his precum was there for a bit, and also it needs a lot more virus to get in someones system to infect them unlike hepatitis which can be transmitted with only .000000004 ml of blood. You are fine.
If there wasn't the friction of penetration, you weren't at risk. It's the tearing in the lining of the vagina or rectum that allows for infection, not pre-*** or semen getting on your clitoris or the labia area.
As long as you used a condom, and it was fully intact when your past partner removed his penis, you don't have any risk (for that sexual activity).
HIV is transmitted via
(1) unprotected anal intercourse
(2) unprotected vaginal intercourse
(3) IV drug works
i would not worry about HIV from this encounter. just a touch is not going to transmit HIV.