Future - not that you can do anything about this now but that is why it is NEVER a good idea to informally agree to anything. Even worse, for you to OFFER it.
If things get messy I would venture to guess her attny will say that you are the one that suggested the support amount and 50/50 custody all on your own. So, why change it now?
You set the precedent and it is tough to change. By doing all this before the legalities began, it is like you gave consent to the situation.
I understand you were doing it in the name of working things out but that won't matter when it comes to the brass tacks of a settlement because your W's attny will argue that YOU set the precedent, not her (as far as support/custody goes).
By offering to support her you essentially supported her choice to move out. So, in the eyes of the court they will say "well, what is the problem now?"
