I agree with the first commenter - staying positive is much better. Starting from scratch shouldn't be an inherent negative - when you moved to Japan you were starting from scratch and you were really excited! There are always reservations when taking a scary risk and not having everything planned out, but you won't grow if you don't take risks. You'll just continue to stagnate. You'll be safe and comfortable, but you've been unhappy with your life for at least the last year, and you don't want to continue that.

I think you're making the right decision :)