Ramification of leaving and starting own dojo, because the sensei's life is falling apart and out of control.
The Sensei is obviously a mess. His world is falling apart and he isn't a functioning drunk. This makes any reasonable and rational decisions or communication impossible. One thing for sure, if you stay you build the resentment. Besides the resentment stuff, over all, if you stay it will be hell , and if you leave it will be hell. You have to pick your poison. What are you willing to live with? The decision is yours, and you have to be the one to make it.
I say move on, start your own dojo. Not to compete against his, but so you can continue to practice.
On to another issue
Now, with that said, not every functioning drunk sensei is a mess. And even if your sensei doesn't drink and stuff, you have to weigh in the fact that people change and have problems over-time. Ideals can be eroded. Sensei get jaded and disillusioned, their dreams are not fulfilled. Their expectations are undercut, or sabotaged and are not met. They have headaches with their students and student issues, parents, and the stuff teaching and running a dojo year after year. And all the other associated issues. They get tired of teaching, it gets routine and boring. Plus it take away from the family and other relationships problems involved in being committed Sensei. And all that stuff. It is all about putting yourself in the other person's position, and not being so focused on you.