Did I react to harshly to boyfriend(now ex) flirting and exchanging numbers at party?

This is not for the faint of heart. I was dating this guy for a few months, very cute seemed nice enough, after a few months i started noticing flirting going on frequently with other girls when we would be out but i sort of blocked it out and tried to ignore....ok before i continue i should get into another "little" problem that actually has something to do with my question..this "boyfriend" of mine was not very, lets say"equipped", in fact he was extremely tiny down there,smallest one i ever saw which was odd cuz he was tall and very handsome but when the pants came off it looked ridiculous like my pinky was bigger no joke and i know this bothered him, i mean this is usually something i would look ped and not bring to attention, and did so until he did what he did to me. So yesterday we are at a barbeque, everyone is drinking and he begins to wander as the night progressed, well i catch him exchanging numbers with this girl saw him actually lean in and practically kiss her, well i lost it, i saw him follow her over to the table where she was sitting with her girlfriends i walked up behind him and yelled "if you want this you can have it" and proceed to pull down his shorts which is all he had because he had been swimming, i mean he was like a deer in head lights somebody actually yelled to him to pull them up because i dont think he knew what to do..the girls were laughing uncontrollably, not good timing for him because things were even smaller than usual after swimming, all you could see was the tiny little head and nothing else not even a half inch,sad yes but was this too harsh?..we did know many of these people and i dont think it will be forgotten anytime soon.