I got my ottb from a rescue he was very calm and sweet and reportedly no vices.[/QUOTE]
I’m not going to touch on your experience, as that has already been discussed by other posters, except to second and third the recommendation that a competent local trainer is needed to evaluate you and help you in real time. No matter how experienced or wise, a bunch of Internet strangers cannot see you and the horse interacting and advise in the moment, which is what is needed.
I do want to address the bit of your OP quoted above, as I have seen this problem crop up often: A horse is quiet and easy when tried and becomes more challenging when the new owner gets him home. You have to look at two things:
(A) What is different in the new home versus the old? Things to look at include the experience level of the handlers/riders, the work schedule, turnout schedule, feed, general environment, etc. Some horses do well on a regular and rigorous work schedule or in a particular type of environment (very busy, very quiet, etc.) and fall apart when they cannot have that. Likewise, a horse will always “devolve” to the incompetence of his current handlers; that’s why you see so many well-started greenbeans go to pot if sold to a novice owner that lacks really good trainer guidance.
(B) Are you and the seller using the exact same definition. What people accustomed to in OTTBs call “calm and sweet” could equate to anything from “kinda hot” to “a few manners issues” to “batshit crazy” for someone less inured to the typical quirks and energy levels of an OTTB. By the same token, the terms “kid-safe” is fraught with potential for misunderstanding. A horse may well be “kid-safe” for a fairly experienced child working regularly with a trainer so that the horse is well-exercised and in a program designed to maximize obedience and calm, but may be too much for a child if any or all of those parts are missing. A horse may be kid-safe for flatwork in a ring, but too strong over fences or too spooky hacking out.
And of course, any combination of (A) and (B) factors can also be in play for a particular horse-rider pair.