A few seconds of pleasure is not worth a lifetime of regret. If your not ready to have a kid, then use condoms, get some of the antisperm inserts for her, make sure she on the pill, the shot, the implant, or something and if all else fails use the morning after pill. She may not know about the morning after pill either so make sure she is aware. (also it doesn't hurt you, it just makes sure you release whatever eggs you may have and begin your period instead of those eggs staying inside fertilized and growing a baby)

good news....condoms have spermacide in them so if you came in the condom you likely had it all over you, and she had it all inside her, so your chances of pregnancy are slim. Next time use some forethought, you should not be inside her without a wrap unless you WANT a kid right now. (and if you have both been tested for everything)
after all, love is great, but vd sucks.