At what point, do things start to get nasty?
When money and greed become more important than the basics in life by either or both of the involved parties (some of the greed is encouraged by lawyers IMO).
The first lawyer I approached would not even listen to me when I explained he was the father of our three young children, so I wanted it to be amicable. He insisted I go for alimony and everything I could get. He also wanted a high retainer fee, which was supposed to be passed on to my X, of course.
The one I finally hired agreed to my terms. My XH did not get his own lawyer as we worked out the terms between us before approaching the lawyer. Even then this lawyer's secretary wrote out a nasty complaint about my XH with words I never said, that would definitely make him angry and defensive if he received that without me giving him the heads up those were NOT my words and that is not what I asked them to write in the complaint. I did not use adultry as my "grounds" even though I initially planned to. The lawyer did tell me that I would have to "prove" it and that could make things uglier than I wanted so it would be better to just claim "inhumane treatment" or something like that.
I should mention that my XH married the final OW and is still married to her, and I know that she hauled her XH into court at every turn, but never could appreciate the fact I never did that to my XH.
The whole thing was amicable and cost under $500 including court costs (early 90's though). I have never once taken my XH to court. We made it all those years and our kids are grown and doing fine.
I know the courts would have required him to pay more child support and if I had wanted alimony, he would have had to pay it as I was a SAHM most of the years of our M. I did get a form of alimony in that he had to pay our house mortgage until either I got remarried, moved voluntarily, or when the youngest turned 18.
His CS was comparitively low but his visitation was extremely liberal. Though I had legal custody, he had them almost every weekend and saw them many holidays and other times. I believe he was more generous with the kids during the times he had them, because of this.
The kids are all grown and gone now, but they all thanked me during their school years, for making such an effort to get along with him. To me, it seems well worth driving an older car, working two jobs, and shopping at the Salvation Army (instead of going after him for more money). Our kids are better off because we were not fighting, and learning to do with a little less didn't hurt them either.
They watched what their friends went through and they knew it was extremely rare for divorced parents to get along as well as we did.
There were only a couple of times I got into it with my XH. One of those times, I remember his "lover woman" as I used to refer to her, must have informed him that she wanted "our" stereo and thought he should have it.
I saw through that SO FAST! He never played that stereo when were together. It was one of those stacked systems from the 80's with huge speakers. I loved it and used it ALL THE TIME and he never turned it on, never touched it. So I knew it was "Lover Woman" who wanted it and I instantly stood my ground and said he was not getting it. He didn't put up any further fight.