To be honest, if you have exchanged legal letters already, it might be best to find out what your lawyer recommends in these circumstances.
However, there are a number of things which strike me as odd about this arrangement. What was the agreement you had on drawings from the business? Did you have an agreement about working for third parties (i.e. his consultancy company). Surely he has to have your agreement to invoice his hours in this way?
Do you have an auditor who you could call to look at the financial affairs of the company, since it would appear his wife has a conflict of interests?