I'm going to contradict my husband in front of our child
Why do you want to contradict your husband?
I want to undermine his authority with our child.
You don't have to agree with your partner, but you shouldn't disagree in front of your children. This can confuse your child. It's better to discuss it with your husband privately.
You can't tell me what to do. Meanie.
I cannot tell you what to do, I can only provide advice for you. A child will learn best if the information they receive is consistent through both parents. Discuss your methods and ideas privately away from the child.