Boyfriend has friends nudes????

Okay so in the past my boyfriend leaked pictures of me around the school (im 16) which I sent to him privately but after a while I forgave him because he seemed genuinely sorry,saying that he has changed etc.So we went out officially and started sending pictures again(I know I know but it took him 7 months to persuade me).im quite laid back but I am absolutely terrified of him cheating on me- today, he admitted to me that he has a few different girls nude pictures on his phone, so I asked him to show me and there were hundreds of different pictures of girls (majority of my year,most of my close friends and year below) which he'd got off other boys. Should I be worried??i just don't understand why he would need them and it makes me feel self conscious knowing that I'm not the only girl's nudes he is looking at😖Need advise asap!!