<human>: Give me the gist of the text in a nutshell

10 days ago, my 13 year old nephew died of complications after brain surgery to remove a sizeable tumor. It has, obviously, been very rough.

Meanwhile, my sister, who lives close to my mom, has been trying to hold it together, plan a memorial service, grieve on her own, return to work, and take care of my 8 year old niece.

Meanwhile, my mother has apparently lost her mind and is going over the top with her grief, lashing out at my sister, and generally getting "stuck" in the anger phase of her grief. She's coming across as very selfish in the process, and I just don't know how to talk to her about it. I know she needs time to grieve and let it out, but she needs to do so without destroying the relationship she has with my sister and niece.

What do I say to her? How can I help her? I live out of state, so being there physically isn't possible. She's also completely without money, so spending money on counseling just isn't an option.
<bot>: Reddit, how do I help my mother grieve the loss of her grandson? How have you or your loved ones dealt with this kind of awful loss?