So sorry for your loss, that must be so upsetting.
Please feel entirely free to do whatever is best for the you that now exists, not the you that existed before Friday. If you feel that exerting control over something would be helpful, NaNoWriMo could give you a chance to be in charge of your story, your characters, and at least a portion of your time each day. But if you feel overwhelmed or exhausted, go ahead and ditch it, or ditch the wordcount, or be a rebel and change your goals as often as you need to.
So far one of the biggest things I’ve ever learned about handling my distress/grief is that it’s actually okay to break promises to myself. That might not sound very inspiring, but I try to think of myself as an evolving being with an ever-changing set of variables affecting me and waiting for me to affect them. And it makes sense that evolving beings can adapt their commitments to new situations and stresses.
Regardless of what you do in November, I hope you find yourself surrounded by support and compassion.