Thank you for your question. I look forward to working with you to provide you the information you are seeking for educational purposes only.
While you may think you would do better in this without a lawyer, that is not the truth. It may have been you did not have the right lawyer, but even lawyers would not represent themselves in this type of situation.
You need an experienced elder law attorney who is familiar with these situations of someone who is beginning to show signs of dementia, which is what you are describing your mother is exhibiting and who has experience with relatives trying to exert undue influence over them, which your sister is doing.
You are going to need to answer the summons and go to court and you must have a local attorney and when you speak to attorneys when trying to select the right one, you need to explain this is about your sister trying to take over the trust and get at your mom's money. You need to bring them all of the evidence you have that your previous attorney did not bring up and show them and get them to agree to properly represent you. If you are not comfortable with one attorney, you talk to another until you get one that will zealously represent you, but do not represent yourself.
We see customers all the time who come here who thought they could represent themselves and they permanently damage their cases because they were not knowledgeable of the rules of civil procedure or rules of evidence and did not properly get their evidence introduced and then even hiring a lawyer after the fact cannot fix the problems they caused. So rethink your decision carefully.
You are going to need to call your mother's doctors as witnesses regarding her mental abilities and to challenge anything she is reading that is written by your sister. You are going to need to also call witnesses in this restraining order case to show you are not violent and there has never been any indication that you would harm your mother other than what your sister has put in her head.
This is a complex case, so you need to get an attorney soon and answer that summons and show up in court with your witnesses and prove your sister is exerting improper influence over your mother for an improper purpose to take over the trust. At the very worst, you should be arguing that if the court wants you replaced as trustee, that an independent trustee, not you or your sister should be placed in charge of the trust to prevent your sister from improperly taking control of the trust.