I am sole caregiver for mom and dad. Dad passed away and siblings are difficult. Help!

I asked dad to appoint lil brother financial and he is horrid. I have been with them long term. He has been away for many years. He freaked mom out doing things underhanded and not in his power, taken documents out of safe, written emails to bank as if her bank called me. I am on and have been on account many years. He tried to block me. What do I do? He has taken money and lied to sibs and mom. Help