UFC's Cat Zingano Crushes Black Bikini Before UFC Return -

Here's UFC killer Cat Zingano SLAYING a black spaghetti string bikini -- proving she's coming back to the cage jacked and ready to rock at UFC 222.

"Strong. Motivated. Focused. Mean. Ready," Zingano captioned the photo ... a selfie with inspirational messages scribbled across her mirror.

But this ain't just any mirror selfie -- it speaks volumes for Cat, a single mom who lost her husband to suicide in 2014. Since then, she's struggled with staying in shape and finding the motivation to fight.

Now, after nearly 20 months off, it's pretty clear she's ready to get after it again.

Cat's comeback ain't gonna be a cakewalk -- she's fighting undefeated Ketlen Vieira on March 3 in Vegas ... the same card with Cyborg vs. Yana Kunitskaya.