Robby,
So sorry to hear what you are going through. When I decided to leave wife #3, I just sat her down and asked her to just listen. I explained that our relationship was no longer working for either of us and that I wanted her to be happy. I told her I was leaving and would be filing for divorce. I said that I will not yell and scream and point fingers if she does the same. There is no reason we cannot agree to separate peacefully, even remain friends. We were in love at one time, so we should be able to be civil.
After that, I told her it was her turn to speak if she had anything she would like to say. She didn't, so I told her that if she changes her mind, we can sit down and speak calmly about this so that we can work out the details.
Over the next month, I remained polite as I would with any longtime friend. I think we had three sit-down talks during that time. And then I left and kept my word about filing for divorce, keeping her informed, making sure she understood the forms and what she needed to do. We had a few phone conversations after I left, but we remained pleasant toward one another.
What I am hoping is that you can do the same thing. If counseling won't help and there is nothing to save, then just sit and talk to her. It is extremely important that you remain calm. You are discussing a business contract and nothing more. You are not accusing her of anything; you just feel that it isn't working. Allow her to voice her feelings, but if she gets upset, stop, remind her you are having a calm discussion, and give her time to calm down before continuing. Don't let her walk away, but sit quietly until you can continue.
The calmer that you remain, the calmer she can be. She may test you and try to argue or raise her voice. Don't let it bother you; this is a business discussion. Ask her if she needs a minute to calm down, then sit quietly until she is ready.
It will not be easy for you, but you can do it. You must stand your ground. Don't give in to her manipulations. Her only choices are divorce or counseling. She might choose counseling to stall. If you do not think counseling is an option, then that leaves only one choice. There is nothing wrong with being compassionate. You can remain strong while feeling for what she is going through.
I wish you all the best.
Hugs!