This is so familiar, my 'brother' who has claimed to be a Christian throughout the years, wound up ousting me and my sister from our inheritance. My dad being such a sweet soul, was a prosperous yet gentle/kind person. He had our childhood home in L.A. county for yrs and was paid off. Right before the recession it was worth a mil+++. The last 10 yrs of his life my brother moved in to 'take care' of him, and all the while was scheming to take control of everything. Long story short, he cajoled my dad into signing over the home to him. There was nothing we could do, although he and my sis were very close and she went along with anything he did. My dad had told me before this, he had wanted him to disown me and I could see the utter shock in his eyes.
Anyway, for a few yrs I tried to make my brother understand exactly the dishonor he did to my very fair parents even quoting Scripture. Jesus was confronted by a man who asked him about a brother cheating him out of his inheritance and Jesus gave the parable of the rich man who had a surplus of supplies and said 'little did he know tomorrow he would die' Lk 12:13-.
Now, after 15 yrs and all the resentment and dislike I've carried, I have through yrs of friendly advise decided to 1)pray for him I know my parents would want this 2)absolutely forgive him 3)be polite when exchanging family and holiday matters 4)not being palsy walsy or taking him up on holiday dinners. We can't put ourselves in jeopardy of unforgiveness and it actually is hard on us not on them. They are blinded by haughtiness, greed, contempt and our part, as I have come to realize, is to pray.