land division and last wills

My father & mother owned 10 acres. 25 years ago, my husband and I approached them about possibly buying a piece to build a home. My father would not give it to us at a reduced rate. He wanted market value price because he said this 10 acres was to be the inheritance to be left equally to my 2 brothers and me at their deaths. My husband & I could not afford it, so we bought elsewhere. After my father died and my one brother died, my oldest brother went to my mother and asked for his portion of the land inheritance so he could give it to one of his newly married daughters who was starting a family and could not afford to pay full price for land. My mother reluctantly agreed to have the land subdivided in to 3 pieces and signed over one piece to my neice. Everyone in the family advised her that it was unfair, but she seemed to think it was fair and that the other two children (me and my dead brother's issue) would still be getting their share. My older brother asked me if I was ok with this transaction and I told him that it was ok with me as long as he and my mom acknowledged that he was getting his share of the property early and he was not entitled to another share. Both he and my mother agreed. I trusted them both. Within a year, my brother told me he and his wife had taken my mom to have a new will written and had made me co-executor with him so that I would not think there was a conspiracy. I didn't know what he meant but I asked my mom if she had taken into account that my brother had already gotten his land share. She assured me everything was done fair and and divided equally. Again, I believed them and never saw the will.
This summer, events taking place made me question my mother about the distribution of the will. She assured me everything was divided equally into 3. I asked her if she had deducted my older brother's share. She said she must have because the will was fair. I asked to see the will. The will simply divided her existing land into 3. i pointed out that my older brother had already gotten his share. She seemed confused. I pointed out that she had given my niece a valuable piece of land and the other 8 grandchildren had gotten nothing. She was still confused. When I told her that my niece's land was worth alot of money and that she had favored one grandchild at the expense of the other 8, she did not understand that. When she found out that my niece was going to sell her home and land, she was very confused as to how my niece was able to sell it. she seemed to think it was still HER(my mother's) land and that she had only given my niece permission to build on it. My brother told her it was simply an agreement my mom had with my niece to live there and take care of the grounds in repayment. She said she did not know why she had done that (given her the land) or what she was thinking and apologized over and over again. she said that it was obviously a mistake she had to correct it and asked me to get a lawyer. She called my deceased brother's children and told them she was sorry, she had made a mistake but was going to write a new will to correct it. she hired an appraiser to appraise her existing two lots as of 2009 and to appraise the lot given to my niece as of 2005, when it was given to her. She died the day the appraisal was to take place.

What are my options?