No parent wants to see their kids unhappy, especially when the reason behind it is the parents' divorce. It is perfectly normal for children to struggle during this difficult time. They may profess to be fine, yet still struggle to cope with the changes.
Below are some suggestions for getting through this critical period.
Don't drag them into your litigation
If the divorce is still pending, strongly limit what you tell the kids. It is one thing to give them information essential to their daily lives (e.g. an explanation of how the parenting time schedule will work or how their extracurricular activities may change), but you should not lobby the children to see things your way or vent about your former partner within their earshot. Children are smarter and more intuitive than you realize, and usually observe all kinds of nonverbal cues. Save your venting, and the processing of your own emotions, for your therapist or (adult) support network.
Children may also spontaneously share disturbing information about life in the other parent's home. Obviously, if it clearly amounts to physical abuse or serious neglect, you should contact DCS or the police. Regardless of the severity, though, do not follow up with a detailed interrogation intended to extract more information. You are not a trained, forensic interviewer and this is not television or Hollywood. In your zeal to uncover the truth, you may damage (or destroy) what could have been a viable investigation by professionals.
Put another way, fewer people in the family or criminal court system will believe a child's account if, by the time it reaches law enforcement or a social worker, the non-offending parent or other relatives have conducted a full-scale, question-and-answer session with the child over several hours or days, complete with audio recordings or written statements. Even if there was no actual intent to manipulate the child, the child may come off as thoroughly coached by the time he or she can be visited by a trained professional. That can be tragic if the original allegation was actually true.
If the child's disclosure does not amount to a crime report, but is relevant to safe parenting, there is nothing wrong with keeping a diary or informing either your attorney or a court-appointed, behavioral health professional responsible for evaluating your family. It may be something the judge should hear. But, again, it is not your job to personally draw out the sordid details. Such a conversation puts added pressure on the child (even if he or she brought up the subject in the first place), and heightens the risk the court will not appreciate the difference between an encouraged account that was true versus one that was false.
Many children will test their parents on this "don't talk about your court case" rule - especially older teens who want to know what is going on. It can also grow even more frustrating when you know the other parent consistently violates this rule and is getting all the air time. (This happens a lot in domestic violence and coercive control cases.) Don't get suckered into retaliation. It is fine to tell your child: "Neither one of us is supposed to be sharing information about the court case. I am always asking you to follow my own rules, and I want to set a good example for you. When you are older, I will explain what happened. But not now."
An answer like this may frustrate a teenager, but they will (eventually) respect you for your discipline and efforts to keep their childhood as normal as possible. They are not stupid. They can recognize good parenting even when they resent it, and the day will come when no family court can tell them what to do.
Make sure your new partner understands the rules
You are entitled to move on with your life and date whomever you wish, but recognize that the introduction of a new dating partner almost always changes the landscape of a post-separation parenting plan - especially if there are personality conflicts or the new partner was already on the grid when your separation occurred. That dynamic becomes even more complicated when the new partner is drawn into a dialogue with the children about your family court case.
Neither parent has the right to micromanage the other's love life, but there is a reasonable expectation that the new partner, too, will follow the basic rules if they will have regular contact with the children. These rules include showing respect for the other parent in conversation with (and the presence of) those children, and not deliberately undermining the other parent's legal rights - especially if that other parent possesses some measure of legal decision-making authority. The family court judge does not have authority to direct the words and conduct of a third party (such as a new boyfriend or girlfriend), but the court does have the power to penalize a biological parent for allowing a new partner to physically endanger or psychologically abuse a child. That punishment can include a restriction or loss of parenting time, or modification of legal decision-making rights.
Focus on what will not change
Kids need continuity and stability to thrive. Keep reassuring them that you will always love them and make good parenting decisions whenever possible. Remind them of all the activities and social relationships that will not change. Make sure they understand they did not "cause" the divorce or separation. You don't have to invent good things about the other parent just to make them look better than they are. (They will know if you are patronizing or lying to them.) But you should not actively trash the other parent, either. Nor do you need to. Misconduct and bad role modeling speaks for itself.
Keep the lines of communication open
Allow them to express their feelings openly about the divorce. But don't pressure them to discuss those feelings or answer questions - no matter how desperately you want information. If they are really struggling, enrollment with a child therapist may not be a bad idea.