Re: verbal abuse from a teacher
A thought about your dan certificate: We don't know how/who/if your school is affiliated (and you don't have to tell us), but I assure you that whatever certificate you may get, there will be many places where it won't be formally recognized. So AT BEST it's of limited use, and you're balancing that ($400) against, well, a lot of possibly really negative outcomes.
Everything you've learned cannot be unlearned. So wherever you go, you have the really important part, (the knowledge and skills,) regardless of wether you end up with the irrelevant part (the piece of paper.)