Eight months ago, my father passed away and left everything…

Eight months ago, my father passed away and left everything to mom. Mom (age 73) is now living with a friend and wants to divide the house equally between her four adult children. I suggested she get a certified appraiser in, tell us the value of the house, then divide it equally. Here's where it gets interesting: My youngest brother sold his house, moved into mom's house and spent $12,000 in renovations on it. He says he is entitled to the house because Dad said so in his will. Apparently, he talked dad into giving him the house if mom died before him. Mom says that to be fair, the house should be divided between the four and that my brother should buy his siblings out. The problem now is my brother is bullying my mother to "honor dad's wishes". He has been caught yelling at her, to the point where she said she wants to do away with herself. Mom has been caving into him in recent weeks. I have tried on many occasions to reason with him, but to no avail. On behalf of my siblings, I have even suggested that we divide 5 ways, with him having 40% while the other 3 have 20% each. He still feels as though we are stealing his inheritance. The most important thing here is what can we do to protect our mother? Secondly, how can we settle this property issue legally? I hired a certified appraiser to check out the house and tell mom what is was worth before the renos were done. My brother stopped this and would not let him in. He bullied mom to agree with him or he would leave her life. He has convinced mom the house is worth 40% of the true value. Thanks for your help!