My sisters hold grudges for things that happened years ago. Why will they not let things go and focus on what truly matters?

I have two sisters who married two brothers and I guess I have always been the odd man out. I was on my parents accounts and took care of them for years. Both sisters at one time moved several states away and I always took care of everything that my parents needed. The older my parents got the more I had to do. One sister moved back to our small town but I still continued to care for my parents. She helped sometimes. This sister is a hoarder (just like on the tv show). She lives with 11 dogs in a nasty house that is not even liveable. My mom is 88 and still in pretty good health. My dad passed away two years ago. He had not been gone a month before both my sisters took my mother to the bank and changed everything on the accounts. My name is no where on any account. Not even payable on death. They took her to the lawyers office soon after and she made a new will. She left my sister that had moved back in charge of everything. All bank accounts have her name, she was named executor of the will, power of attorney, medical power of attorney and given authority over all medical decisions. THey did all this without my knowledge of any of this. I knew they were acting strange but never thought they would do that to me. Mother called and accused me and my husband and kids of stealing from her. They changed the door locks and did not give me a key. I told her to make a list of the things she thought I took and I would bring them back or buy new ones. She never came up with anything. I went and talked with my sisters and tried to straighten things out.....they both said they were not mad about anything they were just busy in life. Anything I tried to do for my mother was always ruined by my sister. For example, I trimmed her shrubs and cleaned her house one time. My sister jumped all over me because I trimmed the shrubs at the wrong time of year and I pulled weeds out of the flower beds that were not really weeds and somehow I killed a rose bush and I threw away newspapers. The plants were not hurt....the rose bush even came back. I asked my mom for a key and she said she did not have any extra. I tried to explain that if she fell I could not get in to help her. About a week later she fell. She had to lay on the floor for my sister to finally show up with her key. These sort of things just kept going on until I backed off and did not contact anyone for a while. I began having chest pains, shortness of breath and severe asthma and unexplainable pains. I was checked out by several doctors and found nothing wrong with my heart or my lungs. I went to counseling and they told me that I was in a severe state of trauma. After weeks of counseling and figuring out none of this was actually my fault they taught me that I could not change anyone, I could not make anyone love me or even like me. I know I have not done any wrong towards any of them. My sister that lives in my town never contacts me....not even when mom was rushed to the hospital. My sister that lives in another state never contacts me when she comes in for a visit. They will not answer my phone calls or return my calls. I have written letters and they have gone unanswered. It hurts my heart that I have lost my family. They are in charge and my mom is going downhill fast. Nothing is getting done. The bills are at least 2 months behind, house has mice and roaches in it. Mom is not taking a bath so that just adds to the smell. The grass is not cut, the bushes are out of control, and my mom eats sandwiches,TV dinners, chips and cookies. Nothing healthy. Her ankles and legs are huge because of all the sodium. A nurse comes out once a week to check her. They do nothing about any of this. My mom tells me they say she and her house are fine and good. Recently my daughter and daughter-in-law went to help out with chores. They went every morning for three weeks doing yard work and housework. My sister called and yelled at them for using her gloves that were at my mothers house. They did not use the gloves anymore and my daughter-in-law got poison ivy all over her arms then it spread all over her body. I called my sister after I found out she was so mad at my mom, who had nothing to do with it. My sisters husband got on the phone and I handed the phone to my husband. He told my husband he was coming over to kill him. He never had acted in this manner but in minutes he was there. I stepped in between the two of them and my brother in law was pushing and shoving me and told me he would take me out and then kill my husband. The law came and just told him to go home. He said he would come after me and my husband. My sister is mad at my mother for not standing up for her husband. I did not file charges. Now I am taking care of mom and getting things in order until today. Mom and my sister are talking again and now my mom will not even hardly talk to me. I can't continue on this roller coaster. What do I do?