Courtney Clenney killed her boyfriend Christian Obumseli in Miami back in 2022 ... but whether she murdered him or killed him in self-defense will be the subject of her trial -- and, we examine the case in a documentary now available to stream on YouTube.

We've put our doc "TMZ Investigates: Killer OnlyFans Model: Deadly Love Story" on the video streaming site ... which takes viewers through all the beats of Clenney and Obumseli's toxic relationship.

Clenney -- who was seen hitting Christian during a trip to Aspen, Colorado -- has claimed self-defense. She's facing a second-degree murder charge in Florida.

Courtney's parents -- Kim and Deborah Clenney -- gave us an interview for this documentary ... and, they claim their daughter feared Christian was going to kill her one day.

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