Male friends

I have a boyfriend and I met a guy the other day and we talked about doing some music together. I told him I'm taken and only am interested in music. Today he sent me a selfie and I haven't responded. Am I being rude or should I say dont send me selfie? I wasn't raised knowing boundaries and being able to say no very well because of some past issues so I find it difficult to say please don't send me this. It wasn't bad it was just his face but I dont want my boyfriend thinking I'm interested in him. I'm chosing not to do music with him. But I dont know if im bugging or not. I already know he kinda likes me. To be frank all my male friends do for the most part and many have told me. Should I not be friends with these people that like me? Should I just not have male friends ?