Obviously none of us know all of the details about this - but I think that if he had been guilty, he would not now be dead. Any man/boy who is prepared to take advantage of a woman/girl will not be torturing himself about it, and I doubt that such a man would kill himself. It is unlikely that the accusation will have been known to others - the police are very discreet about these things - and it strikes me that he must have been so distraught and upset about someone he considered a friend - perhaps who he was even in love with - has made such a horrible accusation. I'm not a psychologist, so I may be totally wrong, I know.
Accusations can only be proven false if the case actually goes to court - and it will not go to court if there is no evidence. The police treat every allegation very seriously, and had there been evidence to take it further, then they would have done.
Some men rape, and equally some women make false accusations. The only person who really KNOWS what happened is the young woman involved, and whose conscience may or may not be clear.