For your other children, they are old enough for talking it out to be very helpful. Have a family meeting, point out what you're seeing, ask and encourage them to share their feelings about why they think they're fighting, and then come up with solutions.
Whatever you do, do not disparage their mother. Tell them that the situation is hard on all of you. How can we as a family work through this? Have them help to be part of the solution.
In fact, it is your W' s choices more than likely causing the angst, but you can't say that. They already know.
Think of this as a life lesson for problem solving/training. Your children need to learn these skills in any case. Guide them.
