My heart goes out to you. We buried a young father this week (youngest is 4) and it really hits home. Although many of my friends are blessed with a parent or two, ever since I lost mine I have perpetually been in the state you mention. I weigh almost everything I do against “will this matter after 120?” and “is this a way for me to give a (spiritual)yerusha to my kids?”
Hashem should give you strength.