I cannot imagine what you and your daughter (kids) are going through. I am very sorry for your loss. Very good friends of ours lost their son at the age of 10 a few years ago from a severe ceisure and I felt devestated. I cannot imagine what they felt. It takes very strong people to recover from this. You must be strong for your children and stay busy with activities and visit your relatives often. The children must feel like they are not "alone" and are still loved, by others in your family and your wife's (grandparents, uncles, aunts, cousins, etc.).
This has been a bad week. My friend lost his wife to cancer on Monday, she was in her 50's.