Found some "personal" photos of my boyfriend's ex-gf in his dresser drawer?

You are torturing your self, is there any other reason why you might think he still not over her? If you feel disrespected then tell him how you feel, but if he keeps it or not there is really not much you can do. He hasn't been hiding it either, he knows you'll find it sooner or later, maybe he is just testing you, confront him maturely, and sure of your self, do not show him you are jealous.