Ok, now off the "omgz u cheated!!" line:
Yes, you should do it, even if your girlfriend doesn't care. Condoms are "99%" guaranteed not to get a woman pregnant - hence, 99% guaranteed not to swap fluids, and also 99% guaranteed not to get you potentially infected with a sexually transmitted disease. That means there is a 1 in 100 chance you have swapped fluids... assuming the condom wasn't ripped to start off with. And you were drunk, so god knows. Moreover, you don't know how likely she is to have one, or more. I'd get checked out anyway.