The best Valentine you can give your kid? Make friends with your ex. That's it in a nutshell. If you and your ex are not enjoying a respectful co-parenting relationship with one another, then your kids are suffering because it's impossible for them not to be in the middle. They are aware of the conflicted relationship, they love both of you, and they are feeling the pulls of loyalty from you both. The impact of your negative relationship with your ex is tremendous, and it affects your children more than you realize.
The fallout of a conflicted post-divorce parenting relationship runs from mild to major. It affects children of divorce, regardless of their age, and includes adult children as well. In its mild form (and I'm using mild in the broadest sense), it can be that the child plays messenger because the parents avoid talking to one another, or that the child is privy to negative remarks made about the other parent either to or in front of the children. At its worst, parents wage an all out war against the other and go to court to fight custody arrangements. In this case, often times the children try to solve the problems of their parents and make some assessment as to who they think is right or wrong, which inevitably damages their relationship with the other parent. By choosing sides, they are metaphorically waging an internal civil war against themselves.
I have worked with adults who dread throwing a birthday party for their children because they have to deal with their own divorced parents' refusal to attend together. Even though their parents may have been divorced for over twenty years, because they still haven't made peace with one another, their adult children are still in the middle. I have worked with a family in which the parents continue to battle and yet send their children for therapy to cope with the conflict. I have a hunch that if the parents would make peace with one another and thus model how to get along, the children will learn a lot more than they will from their therapy. I have heard directly from children how bad they feel when one parent denigrates the other parent but they don't know how to stop it.
A couple of years ago, I attended a conference in which adult children of divorced parents spoke about the impact of their parents' divorce on their current lives. All of them were young when their parents divorced. They each described their parents' divorce as either being a good divorce or bad divorce based on the ability of the parents to get along post divorce. The adult children whose parents learned to have a respectful relationship with one another were all doing well both in their jobs and in their personal relationships. The adult children whose parents never made amends with one another all had conflicted personal relationships themselves. When these adult children spoke, there wasn't a dry eye in the house, and they offered great hope for children of divorce.
If you're a parent who is willing to sacrifice for your children, make that sacrifice by extending an olive branch to your ex. This might not be something that you can do alone or do quickly. But taking those first steps and making a commitment to change your relationship with your ex could be a gift to your child that will last a lifetime.