I am a gay male and have a usual partner (we were both tested and came back negative for everything). My question is this: about a week ago or so, I engaged in mutual masturbation with a different man. There was pre-cum (ejaculate) involved, and some of his pre ejaculate may have come in contact with my penis. My question is could HIV or any other STD have entered through my Urethra? I'm not sure if this is possible, just wondering. Also, since this encounter, I have gone back to having regular sex with my original partner...unprotected. I'm not sure if what I did poses any real risk...please help me out here!