I agree with the people who said that this arc overstayed it's (un)welcome.
I get that the author wants a solid background. But this could have been piece mealed in to soften the blow. There were only hints of the MC dying from crossing the road. Not her having a psychotic breakdown and depression.
To add to this, the author also hints that the grandma decided to end her life on her own. Leaving an already fragile and unstable mother on her own, with her child that again we already got treated to the child being neglected due to the MC death.
Only for the author to kick us in the teeth with the fate of the child being unknown. And that the FMC is either deranged or something, as this far into the story she didn't so much as reacted or cared about her daughter. It would have been fine if there was a hint that she had child but hiding it from the MC. only for it be she is acting like this due to their child from the future past™
But nope. So yeah I agree with people on how I am going to feel real weird seeing the FMC after this tragedy dump on our laps.