Caught him

Last night i had a feeling to log into my boyfriends snap not to lurk but i just wanted to go in. So i did and the first name on top of the list was his ex. I open the snap and see they’ve been snapping eachother back and forth for two days now. Probably wouldve been longer if i havent caught him. I sent him a screenshot of the snaps and blocked him. Then he tried snapping me saying how he was checking up on her cause shes depressed and her brother was in the hospital and all that. Yet he knew to do it on snap because he knew i couldnt see it. Mind you she cheated on him and she was his first love. I have no idea what to do and im so hurt that he went behind my back.