I am so so sorry for your loss. It truly is like losing member of the family. How tragic for you since it was so unexpected. I have been there a few times unfortunately. We lost one our dogs last year unexpectedly to cancer and our second one is aging quickly. You are right in that you are mourning that entire period of your life.
Hugs to you and the kids. I pray you have strength and courage as you and your kids get through this very sad time. I am thinking of you.