Seeing his fwb everywhere

I go to college and he works , my boyfriend had never had a serious partner before , we have been together for 2 years , he used to sleep around with lots of girls , I’m always seeing afew girls he’s done things with and it makes me feel insecure about my body and the way I look , I’m not worried about the emotional part like ‘but ur with him now ‘ I just can’t stand seeing them everyday at college and it puts me in a horrible mood since I can pictufr him naked on top of them and how they see it aswell ,