Simply put, you should not discuss your divorce case with your children. Never, under any circumstances, should you use them as messengers; not only will this hurt your case, it has the potential to cause lasting damage to your children and to your relationship with them. Further, you should never speak poorly of your spouse to your children; your children get half their DNA from your spouse.  When you criticize your spouse, you are criticizing that part of your children.
Often, it’s a good idea to obtain family counseling to help your children successfully deal with your divorce and the changing family dynamic.