Nowadays, divorce isn't such a stigmatizing matter as it was in past generations. They are always painful and especially so for children because they tend to blame themselves. They try hard to be perfect for you. There are things that you can do to help your child adjust to not having both parents in the home.
Be honest with your kids. Tell them that this is the final step in a journey that was begun long ago. There will be no reconciliation. If you are sad about the separation, tell them. The children will be upset in any case but this emotion will validate that they are identifying with you.
Never, under any circumstances, bad mouth your ex-spouse. No matter what led to the divorce, no amount of ugly words will make it better and criticizing your ex in the presence of your kids is unnecessary. Even if your spouse will not have visitation rights and your child will never see that person again, don't make the mistake of ruining what memories your child had of your ex-spouse.
Don't use your children as a sounding board. Don't confide in them no matter how mature and helpful they are. You are there to comfort them, not the other way around. They can't do anything to help, so don't unload on them.
As much as you possibly can, keep the daily schedule as stable as possible. Your children need to know what comes next and a stable environment will help them transition from two parents to one.
Shower your children with extra amounts of love and care. It is so hard to adjust to not having the other parent around for them. They need to know you won't stop loving them in any case.
If you are thinking of a divorce, calling in help isn't weak, it is a strong and healthy reaction.
Source: The Huffington Post, "5 Ways to Help Your Kids Thrive After Divorce," Samantha Rodman, May. 28, 2015