How can one be sad and have joy at the same time?

It has been quite a week, my great uncle was taken into the hospital against his desire, to have him check himself out a few days ago. The dr did tell him he would only have a few days left if he left. My uncle did tell them that if he was going to die then he would die at his home, the home he grew up in. this is the same house my mom and her siblings grew up in and I grew up there as well. I spent my summers with my great grand parents as a child.
Today, at 3:10 pm my uncle left our world and entered into the heavens.