I'm so sorry for your loss, Christine.
Often, our pets are such a part of our daily lives, that there absence is felt more than that of some people.
Take the time you need to grieve, but also celebrate Riley's life and the good times. Sometimes, a ceremony can help speed the grieving process.
I've come to accept death as a natural part of the life cycle, but it's still hard to lose a loved one.
Take care!