In reality, it's much better to expose your kids to marital conflict, as long as you do it right. The world is full of conflict, as it turns out, and it's better to acclimatize them to it early than to throw them out into society with the skewed perception that people never disagree. You'll wind up with a kid who assumes that any argument with their buddy means the friendship is over. "Are you calling me a liar? Well guess what? Kevin is my best friend now! You're dead to me, Trevor!"
The key, of course, is that it has to be healthy conflict. Which unfortunately means that you have to get your own shit together first. Smashing plates against the wall and then downing a whole bottle of wine while your partner storms out to the nearest bar is not the kind of fight that's going to teach your kid how to be a functional adult.
According to studies, the best effects on children are achieved by arguments that are mild to moderate, and resolved in front of them. That last part is important -- parents who cut off an argument only to "resolve" it behind closed doors with some good old-fashioned makeup sex also aren't helping. We're sure that works out fine for you, but your kids probably don't know what's happening. All they know is that their parents went to bed angry, there were some weird breathy bumping noises, and then everything was magically okay again. "All right, Trevor. I think resolving this means we have to take off our clothes and wrestle."