I feel guilty

I have two cousins that i would say im very close to we fight every so often and tattle on eachother sometimes but something we will never mention is there brother my older cousin there brother hes 17 now and one of my cousins lives with him when i was 7 or 8 he was laying in my room on the floor he pulled out his phone and asked if i could take pictures of me naked i went into the bathroom pulled out his phone and i would have done it if my mom didnt come up the stairs i feel guilty my cousin get asked to wear bathing suites in front of him and underwear and alot of other things we are scared to tell someone beacusen if we do my other cousin who lives with him will get hurt by him or they wont believe us sorry for the grammer and puncuaction im shaking and scared