See a lawyer. Have a consultation. You really need to know what your rights are.
Even though Florida is a no fault state, there are circumstances that can make a difference. I know second marriages hold different status with regards to assets (or they used to), I am just not sure of the specifics.
Your W is correct that you have to take the parenting class. I believe it is four hours.
There are formulas in this state that determine child support so it will not just be whatever arbitrary number someone wants to set.
Personally, I would begin to set up separate accounts and close the joint ones. Maybe for no other reason than you don't want to be a party to any future debt that she incurs.
There are things that you can do to protect yourself, without looking like you are trying to be a jacka$$.
Fighting for every last brick and penny, is going to cost you more in the long run I am afraid. Not just monitarily either. However, that is a different conversation.
"Acceptance doesn't mean resignation. It means understanding that something is what it is and there's got to be a way through it."--Michael J. Fox