Doubt that you have much to fear, unless the condom broke, but that doesn't seem to be the case. But please do use a condom if you are going to mess around with other women who have sexually known lots of other men. Me I would stick to the good old, safe hand-sex, Masturbation,just to be on the safe-side. If you love your G/F,and I am sure you do,why are you out there messing around in the first place? And do waite untill she is ready to say "YES".
ok to correct what was said before 2/3 (more like 1/2) of all sexually active people have HPV NOT genetal herpes. HPV is harmless to men and harmless to MOST women HOWEVER HPV does cause cervical cancer so it is something serious. make sure she has had the HPV shot before you two have sex to make sure just get it from the doctor and make sure she has taken her THIRD shot before having unprotected sex.
Don't worry about it. Most men know if it broke when they take it off. I would just make sure next time you be more careful. You don't need to worry yourself sick.
Man dont worry about it, it will be nothing obviously just nerves playing you around. =)