First: Thank you on behalf of your first ‘unsuitable’ horse for putting his best welfare before all else. You were his advocate and champion. One horse is better off, because you cared enough to stand up to a manipulative trainer.
Glad that it reads as if you have already gotten some perspective and are seeing this situation more realistically. You are breaking away from the toxic reality of the trainer.
My impression – You have stepped into the middle of a bad situation in someone else’s life, things that have nothing to do with you directly, but are impacting you – the divorce and the impact on her business. And she may be a little sketch anyway – or else she feels more anxious that usual about money.
She’s over-busy and over-stressed and that’s understandable. She’s also manipulative, on top of being distracted. She’s not saying ‘this is not a good time for a new client’ because she’s probably reluctant to admit that to herself. But it’s not. Her life and her problems are not the place for you or any other newcomer to her program, for the time being.
IMO, stop trying to make it up to her, stop with the peace offerings, just let it peace out. That’s easier for her than having you rise up into view yet again, which is a reminder to herself of all the mistakes she is making. (Not your fault!!! But that is how she’s reacting). She isn’t dealing well with her situation, is she – so let her be – for a few years. 
She seems to be more than a little rude and vindictive about things that are her own doing. She is just not a nice person. Maybe she’ll be more grounded when her present misfortunes are in the rearview mirror – and that could take a long time.
Find a more sensible, caring trainer with a program that takes a true interest in you instead of treating you like just the person who writes checks.
What has been going on for you in the last few weeks with this trainer is upsetting, and you are worried at how big it could loom over the future. But very probably in a couple of weeks the other parties won’t even remember these minor incidents. They are not as big a deal to them as the trainer is making them seem. Going forward, more life events that are far more important will happen for everyone, and most memories will fade. Those that don’t, you can avoid. That’s the horse world.
The horse world can have some abrupt stops and sharp edges, sometimes. People in it need to be resilient and heal well. And keep moving forward. Many have been in your shoes and survived. You will, too. 
(Maybe kind of like law?)
Red flag. Sometimes cuts & paste contracts work out ok, but sometimes they just don’t. Every situation is different.
Because of manipulative manipulator. See all of the comments about the trainer’s wallet.
Rushing people into decisions is another red flag, as is disparaging them when they try to think for themselves. You obviously know this and know the way she’s behaving is not ok. Good for you to pull up and look around and ask questions.
In or out of the horse industry, your instincts are true for you and worth following. Be your sensible self. Don’t let anyone manipulate you otherwise. Sounds like you are doing well so far!
True, true, true.
I don’t know if horse people are the most impractical, unrealistic, wishful and fantasist about business or even business-type decisions. But they must be in the top 5%, at least.
This (derail!) thing about refusing to use sales contracts, be transparent about commissions and cuts, and acting offended if a party wants a contract and transparency, is insane and should not be tolerated. But – it is, and by some clients who have the background to know better.
Ironically, for those few (?) trainers that are good with business decisions and money, they can do amazingly well in a business that is supposed to be a dead loser for everyone.
Create that organic filter for yourself.
… honestly COTH is a great education. 
