Step 1: Break the news together
No matter how difficult things are between you and your spouse, you need to put your differences aside and have your children's best interest at heart. Take time to figure out what you are going to say to your kids and plan to break the news together. By addressing your children together, you can show them that even though the marriage is ending, you can cooperate and be civil with each other.
Step 2: Don't play the blame game
No matter what, don't criticize your soon-to-be ex to your children. It's unfair to blame your spouse for the divorce and to expect your kids to choose sides. No matter the ages of your kids, they shouldn't be put in the middle of your conflicts.
Step 3: Don't give false hope
When breaking the news of your separation and divorce to your children, don't give them false hope that you'll be getting back together. Explain in honest, age-appropriate terms that you are both no longer happy in your marriage so you won't be living together or married anymore. Make sure that your children understand that they are in no way responsible for the divorce, and that your love for them is not changing in any way.
Step 4: Get professional help, if necessary
Give your kids time to absorb the news. Expect a negative reaction, which could include acting out or completely withdrawing. Give your children's teachers and/or caregivers a heads-up about your divorce plans so they will understand (and expect) some unusual behavior from your children. If your kids are having an extremely difficult time handling the news of your divorce, contact a mental health professional, clergyman, support group, or seek other resources that can help your children cope with the divorce.
More parenting how-tos
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How to keep your family energized
How to teach better manners