Oh dear, global maintenance. If there's no child maintenance then it still has to be paid, all as spousal maintenance. These orders are a disgrace because they make it very difficult for the paying parent to take on more childcare responsibilities because they cannot simply pay less if their income drops.
Make sure you do pay it all as spousal maintenance as it should wipe out any benefit claims by your ex (i.e. make it worthless to her). However, I doubt you'll have much luck with a variation in the short term because you only just told a court that you accepted that she needs this income and that you can afford to pay it.
Anyone else reading. Never, never, never agree to global or spousal maintenance. Ever. Fight it all the way to a final hearing and make it clear to the court that the potential recipient is just being lazy and you would begrudge paying it. Worst case scenario is normally 5 year term maintenance and even that is rare nowadays.