I’m sorry to hear of your plight. Many of us here have gone through similar, mine (2 daughters then 7 and 4yo) happened in 1996. Yes, devastated is the word.
Grieving in these situations is a process that others can’t really do much more than scratch the surface with assisting you.
Everyones grief process varies in time. For me it was 8 weeks before I found a block of land. Then my grief periods rapidly declined...why? I was distracted with activities. But add to that a second job (both shift work,) and I was too tired to think about it.
google this please
beyondblue topic the best praise you’ll ever get
beyondblue topic distraction and variety.
ps your kids will be ok, they are resilient