Does this count as cheating?

I am in a relationship with my boy friend for about five years. One day when I was getting ready to go to a wedding for my boyfriends best friends wedding (we're all friends), I slept with my best friend(were both females) because we were feeling curious about out sexualitys. We've only done it twice, and I have a healthy sex life with my boyfriend, and I still love my boyfriend with all my heart. I have no feelings for my friend, purely sexual. I haven't told my boyfriend. Me and my friend don't count It as cheating, more as experimenting...What do you think? Am I wrong? Did I cheat?me and my boyfriend live together. Me and my best friend are both females.