Q: My daughter's father was verbally abusive when we were together and continues to be to this day. Exchanging our child is the worst. Just yesterday he stood in the middle of the street and yelled profanities at me. I have tried to get along with him for years. He blames it on me. I blame it on him. We just can't co-parent. What's good ex-etiquette?

A: Every day angry parents come into my office complaining they cannot get along and there is no way they can co-parent. My response is usually to ask which parent wants primary custody?

That question puts both parents on notice. It's simply not in a child's best interest to go back and forth between their parents' homes when the parents can't stop fighting.

So, how do you co-parent when you don't get along? The truth is, you can't. There must be a change in mind-set to be successful.

I often tell this story in co-parenting workshops. It's a very personal one, but the principles can be applied to your co-parenting relationship, as well.

My father and I had a love/hate relationship. I adored him, and he me, but his experiences taught him to be racist, short-tempered and abusive and our arguments often took on a life of their own. When he was 71 years old, I told myself, "You love your dad, flaws and all, and there will be a day when he will not be with you." I made a vow at that moment that I would greet him with a smile and hug him hello and goodbye at every visit.

And, from that moment on, there was a shift — because I wanted to get along with him. I never discussed it with him. I simply changed my behavior. We never fought again.

My point? Someone has to start the shift. There must be something bigger than yourself to serve as the catalyst to make the shift. In your case, it's the well-being of your child.

We have all been exposed to enough pop psychology to know that ongoing conflict after a split will affect a child psychologically, but studies now show that ongoing conflict between parents affects their child's brain development. Very simply, if you can't find a way to be cordial you and your child's father are contributing to your child's mental illness.

So, with this in mind, get proactive. Enlist the help of a counselor to design a personalized problem-solving plan to get along and problem-solve together. Or, look for low-cost co-parenting classes in your community. But make that shift — in the best interest of your child.

Jann Blackstone is the author of "Ex-etiquette for Parents: Good Behavior After Divorce or Separation," and the founder of bonusfamilies.com.