I'm glad you voiced your experience of the sexual tension between male and female friends. It's something that is either totally ignored or totally blown out of proportion. However, I think it's interesting that sex is something you're able to just "get out of your system." Usually when I'm good friends with someone and I have sex with them, I crave it even more!

If you are now so bonded with each of your male friends, and they knew it was casual sex for both of them, I don't see any harm in telling them the truth. It will add a level of openness and honesty to both of your relationships, and maybe to theirs as well.