Unlike child support, spousal support is often very difficult (if not impossible) to modify after the divorce is final, so getting it right the first time is a must!
Here's just a financial breakdown of your situation:
Gross pay: $85,000/yr Net pay: $55,328/yr Net pay is after Fed tax, NC state tax, FICA, and Medicare. It does not include deductions for a pension, medical insurance, or any other deductions.
Annual CS cost: $10,200 Proposed alimony: $16,800
Net pay after CS and alimony: $28,328.
$850 appears to be guidline support, but it would drop to $730 after alimony is deducted. Unless he is paying a very large premium for medical insurance, it doesn't appear that would change the amount.
$1400 appears to be a bit high for alimony for his income, but, at the same time, 4 years is probably shorter than what you could get.