Sorry to hear of your loss as well, TK :(
Sounds like everything was going so well too. CBBs are noted as having a less than stellar survival rate in home aquaria though...I know that won't make you feel any better about your loss, but hopefully you won't take his passing to heart as far as it being your fault. Maybe a Yellow Longnose Butterflyfish would be a consideration for taking your CBBs place? They are much hardier, and very pretty. ;)

W.