I agree that he is WAY ahead of you on the separation . You need legal and financial advice fast . Agree to nothing and sign nothing . Do not, as a PP suggested , have an open and frank discussion with your DH about it .
I don't mean to be rude, but you clearly don't understand the situation you are in , and he will just be able to BS you .
Make copies of as many documents as you can . Things like your company accounts for the past few years and your and your husbands self assessment forms .
Do you trust the company accountant ? If so, you should speak to him / her and get some facts. As long as they are not in cahoots with your STBX.
While you are still a director , you will be able to access the returns that were made to companies house . Your memorandums and articles of association will say whether or not he can sack you as a director . He can't do anything about your shares, and I assume that you own some - that's the tax advantage of paying you both in dividends and salary rather than just in salary - there's less tax on dividends .
It's possible that all your won income has been dividends , in which case it doesn't matter that you don't work for the company at all .