Tichina Arnold, aka Pam on "Martin," hit the nuclear button on her 3-year marriage by exposing what she says is her husband's sex tape with another woman.

Sources very close to Tichina tell us she put Rico Hines on blast with a scathing group text to friends and family, saying ... "It's over between Rico and I. This is where I part ways and all bets are off." That's the tame part.

The bombshell? She claims he's been banging scores of women -- sometimes without protection -- and she has a sex tape to prove it. Her mass text includes the video and she said, "I can't for the life of me understand why Rico would video himself f---ing 'raw dog' ONE of his MANY extraneous whores that 'trick' on him for his money."

Hines is an assistant basketball coach at St. John's University.

She also named 20 of the women, who she labels "extraneous Kim Kardashian wanna be's."

Tichina says she's concerned about STDs and plans to get tested. Her rep told People she plans to end the marriage. It's unclear if she's filed divorce docs yet.

Hines tells us through a rep, "This is a private and deeply personal matter between my wife and me, and I do not want to comment any further at this time."