Let's face it. If you are getting divorced or are already divorced you have, in essence, already broken a big promise to your kids. Sometimes promises have to be broken, but they should be kept most of the time when you make a promise to your children. If you've had to break a promise to your children, you now probably have an issue with trust. When someone's world is shaken so much - and divorce does do that shaking - it's hard figure out what is real and what isn't. It's also hard to figure out who is real and who isn't. What I mean by that is that your kids must be able to trust you at all times; but the divorce had put you into a fragile state right now and yet, you are still responsible to be there for your children. They should always come first, but especially now that your promise of a 'two-parent' life has been broken.
You can regain their trust in this way: if you tell your children that you will do something, do it! It doesn't matter how small you think it is. If you tell them that you will make it to their soccer game, then make it to the soccer game. If you promise them a movie, rent one for them. If you tell them you won't yell so much, then don't yell so much. You get the idea. No parent is perfect, but the key element to your children's happiness is that they must be able to trust you.
Keep their secrets. You can help them to see that they can come to you with any problem and not find harsh judgment. If they want to talk about your ex, let them. Never forget that that specific ex who divorced you will always be their parent, no matter how horrible you may think he or she is, that fact will never change for your children. They need to know that both of you love them. If they want to go see your ex, don't make it hard or make them feel bad about it. (by all means, use your wisdom for an unsafe situation and tell your kids as much of your reasons as they can bear.).)
So, although you're divorced, make every effort to hold yourself accountable in all situations. If you make promises, keep them. If you can't keep them, then don't make the promise. Learn not to share your every thought out loud. You might not want your children to have your ex's behavior, but you never need to say those words to them. Be the example. Children will never just "do what you tell them too." Show them how to live. Show them how to love. Show them how to trust. They will learn all of these things, good or bad, from watching you.
And in the end, holding yourself accountable will accomplish one added benefit: you won't have to endure yet another divorce!