I'm Lucy, and I'd be happy to answer your questions today. I'm sorry to hear about your situation.
Duress, from a legal perspective, does not mean what most people mean when they say they're signing something under duress. You should assume that, if you sign the document, it will be binding on you. A person should never sign anything they do not intend to uphold. Duress essentially means that he's holding a gun to your head to make you sign, or threatening to cause physical injury to you, your son, or another member of your family, or he literally puts the pen in your hand and moves it on the paper without your consent. Being a jerk isn't duress, no matter how bad the pressure is - you can always say no. In this scenario, you'd have to be able to argue that your husband's act of leaving your son with you would be detrimental to the child's health and well-being, and that may not be the best argument to make.
You can use what he's doing to greatly restrict or even eliminate visitation. But you do not have to agree to reduced child support just because he's a bully and his girlfriend is selfish. The cost of living in Baltimore is higher than most parts of Arizona, and you have a right to receive enough money to raise your son properly. Your SON has a right to be supported by his father. He deserves better treatment.
Look at this calculator to see how much a judge might order you to pay, if you haven't already. See how far off it is from what he's offering. Because if you sign something you don't agree with, you could be stuck with it.
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