If you have kids, one of the hardest questions is what, if anything, to tell them, and when. There's no single right script, but a few general principles hold up well across ages.
Kids don't need the details
Whatever happens between you and your partner, children generally do best with simple, honest, age-appropriate information, not the specifics of who did what. Something like "Mom and Dad are having a hard time and are working through some serious problems" is honest without putting a child in the middle of adult content they can't process or shouldn't have to.
Keep routines as steady as you can
Consistency, bedtime, school schedule, familiar activities, is genuinely protective for kids during family upheaval. It won't undo the disruption, but it gives them something solid to stand on.
Don't ask a child to keep a secret from the other parent, or to take sides
This is one of the clearest, most consistent pieces of guidance from child psychologists and family courts alike. It puts a child in a loyalty bind that causes real harm, even when it feels justified in the moment.
Watch for signs they need more support
Changes in sleep, appetite, school performance, or mood that last more than a few weeks are worth a conversation with your pediatrician or a family therapist. Many therapists offer sessions specifically for kids navigating a parent's separation.
If custody becomes a legal question
Family courts almost universally decide custody based on the best interests of the child, not on which parent was unfaithful. If you're facing custody questions, an attorney who focuses on custody and child support in your state can help you understand what's actually relevant to your case.