When in front of each of your children, you and your new partner must present a united front. Whether you agree or disagree should be saved for private moments. Both sets of children need to see you two working together as a strong unit.
I have a son too. He turned 17 in March. He's six feet tall, kind, smart, handsome. He's leaving for college in a year. Or so. And I frequently catch myself looking at him when he doesn't know it. (Because if he knew, he'd say, "Why are you looking at me like that?")
I am so very thankful for this weird, dysfunctionally functional, blended family of ours. Because for the last six years, whether you've hated me or loved me, you've always made me feel like a real mom. And for that alone, I am eternally grateful. I love you with all my heart.
It seems so simple to say -- dare I say, "too simple," -- but the magical Parenting Plan provides all parents (biological and step parents) the specific terms and conditions under which they are to operate, so that there is no room for "innocent" confusion or misunderstanding.
As a mediator, I am astounded by the number of stories I've heard relating to ignored birthdays, forgotten holidays and missed Mother's and Father's Days by children of divorced parents. Parents: Put aside your feelings for just one moment, and focus on your children.