Well, here's another question.
Is it just a choice between leave, or stay and suffer?
Seems to me, there's a 3rd possibility. He cleans up his act. The man has two degrees... he's not an idiot. He should be able to comprehend that there can be consequences to his actions.
You are right to not give ultimatums until you are prepared to live with the consequences yourself. But when you know that you are... it's FAIR to say "This is minimum acceptable behavior. Behave at least this well or say bye-bye." Then the ball is in his court. He has to decide what you are worth to him. I know that is a very scarey place to be.
Now, this is going to sound like a sexist remark. Oh, heck... it is a sexist remark. Like all such comments, it is a sweeping generalization and deeply unfair to some men, but I haven't met them. Men are not from Mars. They are from the planet Oblivion in a dark galaxy beyond the moons of Emotional Cognizance. It is futile to expect them to know how you are feeling unless you tell them. They will not guess. It doesn't even enter their consciousness to wonder. If you want him to straighten up, you're going to have to tell him so. Flat out. He may or may not do what you want... but at least he won't be able to say he doesn't KNOW what you want.
Smoke