I'm so sorry that your little friend has died. I understand that you are hurting terribly right now. When I was fourteen, I had a guinea pig that I was totally in love with. His name was Bambi and I hand raised him because he was born with a birth defect. When he finally died of old age, I thought that my heart would burst with the pain from losing him. But, in time, I began to feel better and remembered the fun times I had with him. That was 20 years ago, and I still remember my Bambi and how much I loved him.
Soon you will find that you won't hurt as bad, and one day, when you least expect it, you will find youself smiling instead of crying when you think of him. Keep your chin up, sweetie. I know you hurt very badly right now, but soon you will feel better.
There are some people who believe that our beloved pets go to a place called "the Rainbow Bridge" when they die. This is a place where they can run and play and be healthy again until one day, when we are called to heaven by God, they are reunited with us. I personally believe that God has a special place for animals in heaven, so I believe that your little ferret is right now in heaven with God, Bambi, and all the other lost loved ones. I know that this does not ease your pain right now, but perhaps it will give you some peace to know that your beloved ferret is in heaven with God, waiting for the long off day when God calls you to heaven.
Take care