Kevin Costner's Divorce Timeline a Roller Coaster with an Abrupt Ending

Kevin Costner and Christine Baumgartner seemed destined to fight out their divorce for months to come in court -- but now that anger-fueled ride's come to a screeching halt with their settlement ... which makes this look-back at how they got here all the more eye-popping.

Going all the way back to early May -- when CB first filed to end their marriage -- this uncoupling had all the markings of being ugly, starting with the fact her decision to divorce Kevin completely blindsided him.

What proceeded over the next 5 months amounted to one of the nastiest celeb divorces in recent memory ... despite the fact they had a prenup in place.

Pretty much from the jump, Christine indicated she had plans to challenge the validity of the prenup -- starting with the fact she put up a fight about moving out of their house ... even though the prenup required her to get out if she were to divorce him.

After A LOT of back and forth in court and a judge's ruling ... Christine did move out by the court-ordered deadline in late July. Keep in mind, Kevin said he'd already given her over a million bucks to get her own pad.

In addition to the housing drama ... there was the acrimonious issue of child support, which had been challenged by Christine since the beginning. At first, she'd asked a judge to make Kevin pay a whopping $248,000/month to support their 3 teenage kids.

Kevin, of course, scoffed at that ... insisting the realistic number was probably closer to $63k/mo. -- and while he had to cough up $129k/mo as an interim amount, the judge ultimately sided with him on this matter, ruling the $63k was enough to sustain the children.

Amid all this mudslinging and money talk, the Costners went on vacation -- 2 different ones, actually ... and their kiddos got to enjoy respective trips with Mom and Dad. Christine took them to Hawaii for a week, and then KC flew them out to Aspen for some QT.

Come August, it was back to the lawyers' table ... with both Kevin and Christine sitting for a deposition to settle the issue of whether Christine "understood" the prenup she signed way back before their 2004 wedding ... something she and her lawyers argued might not have been totally clear to her.

Kevin and Christine showed up dressed to the nines for that depo ... and then testified all over again in court to hash out more points, including money, rumored partners and more.

In the end, a judge sided with Kevin on this as well -- saying the prenup was clear, and ordered Christine to pay a little more than $14k to cover Kevin's attorney fees for litigating this minute detail.

Christine then signaled she wasn't done nitpicking ... asking for more cash from Kevin to cover her attorney fees, which she estimated at $885k.

That was the latest barb just a few days ago ... and there appeared to be no end in sight. Then, just this week, Christine and Kevin buried the hatchet in a surprise move.

As we reported ... they settled, the terms of which are being kept private for now. While Christine seemed to be taking L after L in court, it sounds like she might've clocked a small win in the end -- as our sources tell us she walked away with more dough than what she was due under the original terms of their prenup.