How can I cope with letting something dear to me go?

I adopted two red wolf cubs about 3 months ago. I have taking care of them ever since. They have recently began to get adventurous and its time for them to go to a wildlife refuge. I have already made preparations for them to go to The Alligator River Wildlife Refuge, but it hurts extremely to let them go although I know it's something that needs to be done. They are like family to me, any suggestions?