There is a body of work by Elisabeth Kubler Ross that is widely considered the definitive work on the subjects of dying and grief. I have found these to be of tremendous benefit not only for myself but for understanding my family's reactions to death.

While her books are available on Amazon (On Death and Dying and On Grief and Grieving), I wanted to pass along a couple of specifics in case you're inundated with "read this book" or just not a reader yourself.

Firstly everyone reacts to death and dying differently (speaking of your entire family here, including your wife). Specifically certain family members will reach different stages at different times and it's important that while you may not be at that stage yourself, especially as a father and husband, that you can empathize with where they are at. The stages Mrs. Ross outlines are Denial, Anger, Bargaining, Depression and Acceptance.

As an example, when a loved one passed I was in a depression stage when others in my family were in an anger stage (why didn't they take better care of themselves etc.). It really threw me and I lashed out. Later I came to the realization that just because we were grieving differently didn't make them wrong and me right.

Also realize that these stages are not explicitly linear and oftentimes people get "stuck" in a stage. Most often depression. It's one of the worst stages to be stuck in and oftentimes requires assistance to get out of (this can be family, or therapy - or never unfortunately). You'll want to keep a close watch on your children to ensure they progress through to acceptance.

Considering the age ranges of your children I'd highly recommend family therapy to assist in this process. Especially while your wife is still alive, as she can help to plant the seed now that it's going to be alright when she's gone. Most insurance policies have a small amount dedicated to counseling which you'll likely exceed, thus I'd ask your physicians to recommend a family counselor (hopefully pro bono). Take care of yourself...