You know, it is sad to say, but that is in large part the truth? My father-in-law goes through this with his ex- a horrible bitter washed up woman who is determined to make him pay for the rest of his life. His kids are grown but he agreed to pay her support and alimony until they were 25. She took him to court last year because she needs 'more' and won another $40,000.
It is not enough that she has spoiled their minds against him. His son still has not called once in 15 years and he has only recently been reacquainted with his daughter who is 20 years old and in college (which he also pays for)
My own experience is somewhat different...when I left my ex my reasons were very valid (he was continually, physically abusive) and I still never asked for a dime. Nor did I play games with visitation and so on. Today, because of it I think, we share custody of the kids and each do, financially, what we can for them. While I can't stand him, we can be civil because somehow in all that nonsense we had managed to put the kids first.
The circumstances of the break up tend to dictate how bitter and vindictive things can get. In my particular case, my wife had an affair. She's now shacked up with the guy and it's evident that he pulls the strings on alot of the crap she's been pulling. I don't know if he's insecure (hey, she cheated once, she can do it again) or what. Having to look at my son everyday probably doesn't help (he looks just like dear old dad). But it's not like I'd ever take her back. Outside forces always play a role in the aftermath of divorce.