Finished Torch by Cheryl Strayed.
Teresa is a wife (in a commonlaw marriage) and mother to two kids (Claire is in college; Joshua is a senior in high school). After she’s diagnosed with terminal cancer, her family starts to disintegrate. Once she’s dead, it happens even faster.
This is apparently really loosely based on Cheryl Strayed’s life although only the grief is accurate. In a preface, she mentions that, for example, Joshua’s life doesn’t mimic her actual brother’s. (No spoiler here.)
I think anyone who’s lost a parent will overidentify here, though. Even if you don’t react the way that Claire or Joshua do, the sense of the world being just WRONG will resonate.