The closed book

Brett has always been a very private person and never talked much about himself. But given their bond, Eddy thought Brett trusts him completely as a lifelong friend and has kept no secret between them. Until one night, a random decision on Eddy's end changed everything; a secret that Brett's been hiding from Eddy for years is exposed. How are they going to move on with the knowledge of this? Why is Brett keeping this from Eddy?