I'm glad that you've decided to see a lawyer about the business. Keep the info to yourself and until you decide what you are going to do about the relationship as well as how you plan to deal w/the business relationship, etc.
If he should say something about your leaving the business, you can point out that it's just a business and as a partner, you have decided it would be much healthier for you to start fresh elsewhere.
Yes, he's going to be madder than an old wet hen because he relies on you so heavily to take care of things, but that's the consequence of his actions/choices and he'll have to get use to doing for himself. It's just business and you aren't doing this to punish him, but to help yourself out of an uncomfortable situation.
Enjoy your time away from the office.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
