Is my boyfriend horny or cheating on me?

okay my name is Rhonda, and my boyfriends name is Jimmy. We are 17, and We have been dating for 4 years. I have thought he was cheating on me before, but now I think so. I came home to his house last night, and went in his room to surprise him, and there was a thong in his bed,. I was like " what the hell" Then I found a bunch of condoms and birth control in his bed, and found pictres of him and some girl in his nightstand. Is he sleeping with another girl? Or just buying stuff, becaus ethis one time I was at walmart. and I saw him there, I strarted sneeking up on him, and then I saw what he was looking at, a double d bra. And toys. I just watched him for a bit and then he picked up banana flavoured condoms, red thong, camera, whip cream, er, and a man thong. I am being serious, I dont know why he was getting all of that, we havent ever used that, but whatever. thanks so much. feel free to share any of your experiances like that. I feel really depressed and would like some support. thanks.