Your STBX is a control freak. You know that already! How did you lose $3000?
Anyway, you have a long haul ahead of you..that's why I said go for the gusto. Who knows gas may be $10 dollars a gallon by the time they are 16. It's a lot harder to get more child support later, so do what you can now and don't go lower! What were you thinking!!!!!!
As far as a 16 year old getting a job, not really a good idea. For what they get paid it would barely pay for the gas to get there and back. Or do they need to buy their own car and gas?