Do your boyfriend and the other guy know each other? If not forget about it.
If they do, and your BF finds out you sent the pics to the other guy, you can just say it was a mistake, which is true, of course?
It reminds of a comedy routine where the comedian (female) says that these naked selfies are like, back in the day before Internet, taking a Polaroid pic of yourself nude and posting it through someone's letterbox! We would never have done that. Why do you young kids do it?