When a trainer is verbally disrespecting another trainer, especially one that has a resume & track record of success, that’s a red flag. First, it’s unprofessional. Second, there are a set of unwritten ‘rules’ among trainers, and one is they don’t criticize other trainers in public, no matter how hard it is sometimes to hold back their opinion. It’s part of being in the segment of the horse world known as ‘trainers’.
So, by openly criticizing the 5* trainer, this trainer is basically marking herself as not a part of the "world of ‘real trainers’ ". It doesn’t mean that she isn’t a trainer, it means she’s putting herself outside of that cooperative group (and they do communicate and cooperate far more than their clients are aware, even when not working on the same level).
Which opens the lid on a host of issues and baggage that this trainer is undoubtedly carrying around. That is spilling over into her program and how she handles her clients.
OP, without taking the time to assemble them all, you’ve posted a number of contradictions about your opinion of the BM/trainer. You say that BM/trainer has great skills with green and difficult horses, that she’s done well with your horse, but then in another post you express concerns with how things are going now with the training rides she is doing with your horse. You say that she is your primary trainer/coach at shows, but that she isn’t living up to that role. There are more contradictory remarks/opinions in your posts, but that’s a start. You refer to this person as BM, and add her training & coaching as an apparent side description, which is an unusual way of looking at her professional role.
I suspect that you while you previously had a high opinion of this person and her program, recently some deep concerns are coming to the surface that contradict that image. And that’s a hard realization to accommodate. It’s telling you that maybe she’s not right for the primary role that she currently holds in your horse life. If that is the case, then you are facing some possibly difficult choices.
I once developed similar conflicting opinions about a trainer/BM/coach. I initially had a high regard for her and her program. She was offering a program for riders who wanted to progress in eventing. She had a lot to offer as an instructor & coach. But often she would withhold important information in a lesson. She had odd expectations that her students would know more than they did, but didn’t acknowledge that she wasn’t giving them the information they needed. Although her program was designed for riders who were actively eventing, she would only occasionally go to events to coach. In a warm-up ring, her students were often the ones with no coach. Before an event, she didn’t like tailoring lessons to prep for the event that weekend. And so on. Sometimes she did something brilliantly, but more often she didn’t make the effort. It took a couple of years to realize this.
Because I saw her potential and thought that I would ‘grow into it’ while at her barn, it took me some time to realize that this wasn’t going to happen. I was roadblocked from progressing very far and so were her other students. Her quirkiness wasn’t occasional, it was who she was. Eventually each of her students would figure that out and move on.
I finally figured out that the image didn’t match the reality. That was the time to move on. It was a difficult decision because I had been with that program too long and was too emotionally invested. And because it was challenging geographically. But moving on was one of the best decisions I ever made in my horse life. The longer drive to a better program was what was needed. 
