Hi ijustwantpeace,
Whew, I can see why you chose the name you did... .there is a lot going on in your family! I'm really glad you decided to reach out here
Do you live on your own or with your mother? I couldn't quite tell from your post.
I'm on these boards because my SO (significant other) has an uBPDxw (undiagnosed BPD ex-wife) so come at this from a different angle. Based on my SO's ex something occurred to me that could be happening in your situation too.
At the heart of BPD is the fear of abandonment, and death is the ultimate/permanent abandonment, in the ex's case her mother's death escalated her dysfunctional behaviors as it seems to be with your mom and uncle. Unfortunately, you have two people freaking out the same time and taking it out on each other and anyone nearby.
I want to pass on a few things for you to read, one is information on FOG (Fear, Obligation, Guilt) or Emotional blackmail. I can hear this in your situation and it can be really helpful to understand when this is going on and seeing it for what it is. In my opinion it is helpful to see the dysfunction for what it is, it helps take some of the emotion and chaos out of the situation so you can think and not just give your usual knee jerk reaction to something.
https://bpdfamily.com/content/emotional-blackmail-fear-obligation-and-guilt-foghttps://bpdfamily.com/message_board/index.php?topic=82926.0The other information I want to pass on is about boundaries which is a tool that you can employ to protect yourself.
https://bpdfamily.com/bpdresources/nk_a120.htmhttps://bpdfamily.com/content/values-and-boundarieshttps://bpdfamily.com/message_board/index.php?topic=61684.0https://bpdfamily.com/message_board/index.php?topic=167368.0Spend some time thinking about what kind of boundaries you could create in your situation. You could flat out refuse to help with grandma (your mother made the choice to bring her home that was her decision, not yours, you are under no obligation [F
OG] to participate in care taking... .know that guilt will most likely be used if you refuse. See it for what it is emotional blackmail), you could help a limited time... .once a week... .2 hours MWF... .whatever you are willing to do if anything.
Know that it is up to you to enforce your boundaries, pwBPD (people with BPD) are expert boundary busters. So if you decide to help with Grandma once a week do only that. FOG will be used to get you to do more, see it for what it is, manipulation... .it doesn't have anything to do with who you are as a person.
Think of the little kid that wants candy. He asks mom for candy she says "no"... .he starts to whine and asks again and mom says "no"... .he starts having a full on screaming crying tantrum and asks mom again (we've all seen this at the grocery store  . What happens if mom gives in here? That little kid learns that if he screams loud enough he will get what he wants. If mom still says "no" (enforces her boundary) the little kid will learn that "no" means "no" and will eventually give up.
If you set a boundary think of your mom as that little kid because she will use FOG to try and get you to back down from the boundary you set.
I hope I've given you something here that is helpful.
I know other members will be along with more ideas, support, and tools.
Panda39