To think this request takes the absolute biscuit.

[Justwantaneasylifenowplease]

DSS12
Married to DH 4, together 10. Great relationship with DSS. His DM withholds access when she doesn't get her own way. She is demanding a 2.1% increase on maintenance payments from DH, plus he is to pay an additional 50% of his private school fees (her choice, DH had no right to an input)
Apparently we need to now take into account my earnings and bonuses. This is the same woman who has caused me an infertile whore. (See other thread) The same woman who sent DSS to ours for the weekend with no clothes that fitted him and expected us to kit him out, head to toe. (Which we did) I'm so curious as to what she does with the money DH already gives her, when he seems to shell out hand over fist in addition.
AIBU to think she must be completely nuts and that after the hell, she's put me through she wouldn't have the audacity to ask me for money and genuinely expect to get it?!

Say no. If she stops access then go through the courts. You'll end up paying her much less money that way anyway. Not really sure what her issue is??

To add to my earlier point fees go up with inflation and costs of the school. Your DH really does need to sit down and see if he can continue to pay half over the next six years.