Michael Lohan's estranged wife, Kate Major, called a black cop a "monkey" and a female officer a "dyke" ... this after threatening to murder the officers.

TMZ has obtained body cam and police cruiser footage of Kate's detainment last weekend, and she goes on an incredibly racist and homophobic tirade against the cops taking her in for an involuntary psychiatric evaluation.

She calls the black police officer in charge of the detainment a "monkey" multiple times in the video, and even invokes white supremacy into her rant. She also calls a female officer checking her for weapons a "dyke" ... all while sporting a bag over her head 'cause cops say she was spitting at them. 

We broke the story ... Kate was placed on a psych hold after she threatened to kill cops if they didn't find her kids, whom Michael had taken with him upon discovering she was drunk and belligerent at home.

We've obtained the audio of that 911 call as well ... it's all bad.

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TMZ.com