Don't know if this will help. The state you live in should have info on how they require trusts to be set up and handled. When did this trust get set up, and, do you think your mother was competent at that time? Were you present and did you also have to sign off on the trust agreement? Did everyone involved have an attorney involved and present at time of signing? Was your mother represented by her own attorney - not your brother's, which could be considered a conflict-of-interest? I assume you are listed as a beneficiary and, as such, you do have rights - again, depending on the state you live in. You can explore some of this ahead of contacting an attorney by checking with your state's Bar Association. The Bar Association should also have a program for recommending an attorney, which can be the most difficult part of this for you. Define your questions ahead of meeting with attorneys you are considering to represent you. Meet with several attorneys and know what you're looking for.
The very difficult situation I went through with my siblings taught me a lot, but, unfortunately, it was after it was all over and my father was dead. Believe me, I understand your struggle. Also, in the state I live in - Wisconsin - the attorneys involved were all paid for by my father's estate through the whole process. You should find out whether that would be the case for you. Lawyers are very expensive and you have to use them sparingly, which can be difficult if you are doing this on your own.
I sense your anger. The most important thing I learned from all I went through, was that my anger got in the way of smart decisions. My 2 siblings and their spouses and children had each other to help them through. I am unmarried with no children and I had only myself. That is a dangerous situation for you. STOP and control your anger - however justified it may be - before you make any decision. From what you are writing here, I see all sorts of red flags, the first major one being your mother's competency and ability to sign any such document. Start with that and then, again, move ahead without the anger. Immediately contact your State Bar Association site for information regarding the setting up and running of Trusts. After you have informed your self you may know what you need to in order to speak intelligently to an attorney. That really is the most important advice I can give and I hope you come back and read this.