Connie - My heart is breaking for you right now
Unfortunately, I have a sister who could be a twin to yours. I have already informed my older sister that when something happens to our mom, she better get here as quick as she can or I might inflict serious bodily harm on the other sister. I have to give my mom credit - she has already given me some things I wanted (even things I didn't ask for but she wanted me to have) and she has a will (my bil - older sister's hubby - is the executor) where she lists who gets what so there are no fights or stealing. My younger sister has stolen enough from my mom while she is still with us (don't want to get started on that!!) and ignores us, her family, unless she needs something.
Don't want to hijack your thread with my family issues but did want to say that I hold you in my thoughts and prayers. And, as someone else already mentioned, if your mom had a will, there are legal avenues you can pursue - but only you know if it's worth it. May God continue to watch over and comfort you during this time.