There were a lot more people who buttfucked Bieber than just Diddy. All the dicking messed with his head and turned him towards drugs and tattoos and all kinds of degeneracy. Diddy ran those freakoff orgies for days. From what I heard, he even passed Bieber around to his own sons.
Bieber's mother is a freak who was raped repeatedly as a child, leaving her deeply misandrist and depraved. She did not hesitate to pimp Bieber out shamelessly from the moment she found out he had a talent for music performance, and did this long before Diddy was in the picture. Bieber himself was also rumored to do some pretty messed up things behind the scenes, so he feels he can't come clean without ruining his reputation beyond salvation. Instead, he just wants to bury it with money and drugs, and hope it goes away.