Our ferret, Mr. Sebastian ferret, has cancer.  When he was diagnosed in December the vet said 6 days, 6 weeks, 6 months, but he is dying. 

Shortly after that he began to lose his fur, he has developed small sores on his bare skin, his poo has turned black, and he has a hard time eating. 

I can see his old mischief, the curiosity and downright playfulness, but he seems to be dazed and a bit slow now.  He once would attack all the pets in the house.  He terrorized our cats, chased our dogs.  Poor dogs had no idea what to do they just thought he was a member of the pack and knew not to harm him.  The cats were indifferent until he bit their tails.

The worst part?  He started snipping at me and biting me when I pet him.  Sebastian has never done that.

I am crying like an idiot here, I just made the call to have him euthanized.  Please tell me I am doing the right thing?  Please tell me I am not murdering a pet, a friend.  Tell me I am not needlessly killing a harmless pet?