Miss 8's teacher is friends with my repeated child sex offender Ex's brother who doesn't know he's a sex offender

Sorry, this is going to be long. Please don't judge, I know how stupid I've been and no one could ever put me down as much as I have already. I fell for manipulative abusive bullies and I didn't protect my kids when I should have. I'm very anxious about my daughters teacher next year. I'll start at the beginning.
My Ex and I didn't have the best relationship. He had bad mood swings and would take it out on me. It was mainly emotional but occasionally became physical. At the time I blamed myself, felt like I deserved it and so on. I've tried to put all that behind me and I now have a wonderful partner and he's a wonderful father to my kids and the child we now have together.
In the month before I split up with my Ex began planning to leave as he was starting to take things out on the kids like the time he hit my daughter across the head with the metal part of the vacuum hose for getting in his way. Things came to a head when I walked in one day and my daughter(3 at the time) was naked in front of the TV and he was staring at her masturbating. My whole world shattered and I don't think I'll ever be the same after that. I couldn't even begin to try to explain what my Ex has done to my head. I went to the police and they were wonderful. They arrested him and over the next few months I headed in usb sticks, CD's and pictures that I'd found hidden with child porn on them. Each time I found something I'd break all over again. I struggled to deal with what had been going on under my nose the whole time and blamed myself. My Ex plead guilty 9 months after he had been arrested and received a minimum of 6&1/2 years.
Child protection opened a case when the police called them and were there as a support but after they closed their case they continued receiving complains about my parenting. Complains like not feeding the kids, not clothing them, the house being unfit for them because of mess and even doing drugs in front of them. In the end everything was unfounded. Eventually I learned that it was my Ex's mother who is a school teacher and well respected in the community. I had trusted her and in the beginning believed she was trying to support me. She is always so polite and friendly but I now see how manipulative and the bully that she is. I fell for it for years before hand. Once again I kick myself for not seeing it all earlier. She did things like coming in uninvited minutes after I'd given birth or buying my kids xmas presents that I'd had said I was getting for them. I just thought that she mustn't of heard me or forgot and I never kicked up a fuss because I don't like confrontation and have pretty bad anxiety. There was one time I'd asked if she cold look after the kids and she said no because she has MS which was fine with me but the next day Child Protection rang me and said that they had received a complaint about me needing help with respite from the kids because they had been told I was suicidal which I wasn't. Depressed yes but not suicidal and they wanted me to come in for a meeting. We arranged a meeting for the end of the week and the next day my Ex's mother rang and specifically asked about Child Protection. I said there had been another complaint and I had a meeting with them. She asked when the meeting was so I told her. I should of clicked at this point that it was her who complained but didn't until she kept persisting that she take me to the meeting to support me and I repetitively declined.
Come the day of the meeting she pulled up in my driveway behind my car so I couldn't get out and kept insisting that she take me. By the end I was in tears because I was going to be late so finally agreed to get in her car. In the meeting she wouldn't leave and kept insisting that she take the kids for the weekend to give me some time off. At the time I was very upset because of my Ex's mother so I probably looked like I needed it and Child protection was strongly encouraging me to take her up on her offer. I reluctantly agreed still not realising just how manipulative she can be. After the meeting she kept talking about how Child Protection can take my kids and that she was here to support me and help. I was and absolute mess by the time she drove off with my kids. I cried all weekend.
Then sunday came and I contacted her asking what time the kids would be home. She told me that Child Protection had arranged for more respite and that the kids were going to her other sons for a week. Stupid me, I believed her again and having OCD, PSTD and being at the most vulnerable point I have ever been I let them go with the intention of calling Child Protection when they opened the next day to find out what was going on. I rang 3 times on the monday, 3 times on the tuesday and by the wednesday I was beside myself that Child Protection had not called me back so when I rang I left a message that if they didn't call me back I would report my kids missing to the police. Surprise, surprise, they called me back within 5mins of that message. They told me that they had not arranged it and that they wern't allowed to arrange anything without my consent or court orders. I then rang my Ex's brother to tell him I would be there in 15mins to get my kids. He told me that I was not allowed to until Child Protection said I could have them back. I tried to explain to him and he cut me off telling me that he doesn't want to get involved and doesn't want to hear it. He called his mother and by the time I got there he gave my kids back without incident.
My Ex's mother has kept all my Ex's charges a secret from the whole family and none of them visit him in gaol and she has told them that we were both abusive and I did the dirty on him and got him locked up. None of them can see how manipulative she can be. After calling Child Protection didn't work she tried taking me to Family Court where she said to my face all the lies that I'd heard as romours and she tried to present it as evidence. She even argued that my Ex is a good father who loves the kids and he would never hurt them even though more people have come forward about things he did to them as minors including 2 of his younger cousins(both female and male) and he has had an extra minimum of 5years added on top of his previous sentence. Family Court didn't work either and at the end the judge told her very sternly that she always has the right to go back to Court back she wouldn't recommend it as she had already wasted enough of the courts time.
If your still reading, thank you. I'm getting to my question now after the background story/essay.
I still let my Ex's family(except his mother) come and visit the kids as I don't blame them for my Ex's or his mothers actions. It has torn the whole family apart. They choose not to see the kids with the exception of about 1/2 an hour at xmas time to give them presents. They all think the worst of me and believe it and don't want to hear the truth. They can blame me as much as they like for the family being torn apart as long as it doesn't effect my kids. Which it does because they have pretty much lost a large portion of their family and they don't understand why. It does worry me what happens when he gets out of gaol and is invited to all the family functions with a heap of young nieces and nephews but I don't think I can change that at this time.
Anyway when miss 8 goes into grade 3 next year she has a new teacher to the school. It turns out that this new teacher is my Ex's, brothers best mate. I only know this because my Ex's bother visited yesterday for his annual visit and was telling my daughter all about her new teacher and that he was his best man at his wedding. He already knew who my daughters teacher was so I can only assume that the new teacher has already informed my Ex's brother that he will be teaching her. I feel really nervous as from previous experience my Ex's mother will twist everything to make me look bad, I fear that she will use it as an opportunity to get information. Should I be worried that confidentiality will be/has been broken?
I don't know what to do about this. I want to move school but that would be a big step as this school is a block away so my kids wouldn't be able to walk or ride their bikes, change of friends and so much more. Should I ask for a change of class(miss 8 is really excited as her current group of friends are in the same class)? Should I do nothing at all and wait to see what happens? Is this just my own anxiety issues over thinking this? I still see a psychologist but she is on leave until after school goes back. I don't know what to do.
If your still hanging on reading this thank you! I can't sleep again because I can't turn my head off.