Kevin Costner‘s divorce was as ugly as they arrive — and far of it needed to do with claims of infidelity on either side … one thing denied by all sides and featured in a brand new ‘TMZ Investigates.’

The A-lister’s cut up from his spouse, Christine Baumgartner, kickstarted with unfounded rumors of KC impregnating somebody on the set of “Yellowstone”  — one thing we dive into intimately in a brand new documentary airing Monday on FOX, ‘Kevin Costner’s Divorce Conflict.’

Now, in terms of CB herself — there have been rumblings of alleged dishonest as properly … on two completely different fronts, truly. There was a man who was staying of their visitor home — whom she was alleged to have slept with — he shut that down, saying it by no means occurred.

There was additionally Josh Connor … a good friend of Kevin and Christine who — as quickly as they have been within the midst of divorce — began to hang around so much with Christine on holidays. Once more, sources related to each of them say there was completely nothing romantic occurring earlier than or throughout the divorce.

“TMZ Investigates: Kevin Costner’s Divorce Conflict” airs Monday at 9/8c on Fox and begins streaming the following day on Hulu.