breakup was unclear. now I saw a photo that messed me up. What do I do

please be brutally honest if what i’m doing is necessary or if im just gonna lose my self respect within the rs. me (20F) and my ex (20F) of 3 years been broken up for a week and a half, due to an argument. the relationship is not abusive, i feel like it’s just the spur of the moment that led to the break up. he went to a year end party at his work and got drunk. this morning a friend sent me a picture of him and a girl, he was drunk resting his face in the couch and the girl was beside him giggling and pointing him. that made me spiral, because he never had any girl friends throughout our entire relationship, and i don’t recognize this girl. i thought of going to his house and confront him about it, the point is i don’t know where i stand. i don’t know if this was really a breakup. but i don’t want to lose my value in it, so should i ask him about it?