Welcome, Frosty Rei.
What you have written is indicative of someone who is under a great amount of stress. As a teacher, as well as someone who has lived and taught in Japan for 6 years, my advice to you is this. You need to decide what's more important, you or the job, and then you need to act on it. You have a choice. Remember that; You are in control. There is a solution. You just need to realize it.
All the best, and good luck.