Re: Cold Sensei
I agree with all who said to just walk away and put it behind you. Start fresh at a new dojo that has a healthier atmosphere.
It almost sounds as if it's your teacher who has the issues. Perhaps he found himself attracted to you, especially after time had passed and he and you had shared a comfortable and easy rapport. It starts that way. He may have started to have feelings, and then when he realized it he abruptly put the breaks on that rapport. But he also might not have known how to articulate this to you, and instead simply put up a wall. That is very common. It happens in workplaces and other interactive venues too.
If you do stay, probably the tension will never abate. Walk away. Start fresh.