Colo tenant tears up lease agreement and brother who owns 75% moves in

My father died in 2004 leaving his property to his 4 children. I was the executor and much envy lead to my sisters. signing their 1/4 share to my brother who now owns 75%. He was living on the property and I still helped pay the taxes because he was always delinquent. He was always in jail for failing to pay child support and/or drugs/alcohol related offenses. We don't get along since dad died. He was running from the law the let a couple live there with no agreement, not letting me know, etc. I found out when paying the delinquent taxes and talking to people that they had been there for 4 years. I spoke with them and instead on evicting them (my brother was in jail, again), we signed a month to month lease agreement. They were already there - not much gain for deposits, etc., at that point. I'm a nice person and let the deposits slide provided they maintain the lease and keep the place up. My brother recently fixed his outstanding warrants and talked this old couple into letting him move in. My brother left me a voice message saying he is moving in, no more money and "that's that!". Question: What is my recourse? I live in WA state. I was told by my fathers attorney before his death that I should have a rental agreement in place with my brother. I didn't. He was living there after all even if it was without my blessing. He just moved in the day dad died. He is a bully and not a sober person. Please advise. Also, I have paid the last two years taxes. I work hard for my money but I loved my father and feel that this is wrong. I had a 4 months of rent of only $500/mo for a 2-bed house and property. What now?