Emotional! Am i over reacting?

So i dont know if im over reacting or what, but my partner works at walmart and he comes home last night and right before he goes to bed he has to smoke his (nasty) cig. Well anyways he goes out side and then like 2 mins. Later i decided i was going to get some air as well, well i guess he didnt hear me coming down and the door was open just a little and i seen he was doing something on his phone, but just as soon as he seen me he shut his phone off. (weird) well i asked what that was all about and he said nothing. Well long story short i found out that he hasld taken a picture of some girl that had come through self check out that only had a tank top on and black booty short undiea were he butt cheaks were sticking out. Well he makes a tumblr account and post it on there and says "public booty at walmart tonight"

Question is am i in the wrong for geting upset over this and for him hidding he had done this.

(he had taken the photo with his phone and then sent the photo to his email and then deleted it off his phone so i wouldnt see it) ling story on how i figured that out.

But i had asked him if he sees anything wrong with doing this and he come out with a strong answer of "nope"

Am i over reaction or is he in the wrong for doing this?