Two adults, one child, both parents make $30,000 (total parental income, $60,000) = about $300/month in child support. (This is an example, but it's reasonably close to actual state formulas.)
But, to house, feed, educate, furnish medical and dental care to, etc. even one child, the custodial parent will spend far, far, far more than $600/mo. Child care alone is usually about $800+.
So if the wife has custody, as is still common, and the husband only pays child support, the wife has far less income than she did prior to the divorce and the husband has far more.
I do not know what's happening to your teacher, although I am shocked that a school teacher would confide in his students about his divorce in the detail yours apparently has -- that's extremely inappropriate behavior, IMO.
Here are some possibilities:
* Your teacher is lying his ass off. This isn't even a sin in divorce, as most combatants feel grievous injuries and it's common to vent to friends in a biased manner. ("Friends" meaning other adults, not schoolkids who admire you.)
* Your teacher and his former spouse have 8 kids. The formula I described will run up the child support obligation (to a degree) for the number of kids to be supported. Of course, as with the example in which the couple has only one child, the amount the wife/custodial parent spends on a child is usually far higher than the amount the noncustodial parent/husband pays in support.
* Your teacher is paying both child support and temporary alimony and/or a property settlement. The couple may have owned a home together which the husband wanted to keep, and the wife may have agreed to accept periodic payments to retire her buy out (her share of the home's equity). Or, the wife may have had a HS education and the husband a PhD, so the judge gave the wife 2 years' temporary alimony to allow her time to get ready to support herself and her child.
* The judge ordered the husband to pay the wife's legal expenses. This is rare, usually reflects very bad behavior on the part of the husband and would normally not be handled as periodic payments to the wife -- but it's possible.
What do we know about your teacher? We know he has grossly inappropriate convos with his students in which he demonizes his former wife. That's all we know for sure -- but it should give you reason to pause and reflect, ab9926.
I'd bet next month's mortgage payment, there are 2 sides to this tale of woe he's spun to you -- not one divorce lawyer in America thinks no-fault divorce has been some sort of economic boon to women and children. However, that does not mean there aren't hordes of men paying child support who deeply resent "giving money to their ex".