They say when you're angry, write the letter but never send it. That adage likely could have saved UFC light heavyweight Anthony "Rumble" Johnson some trouble this week.

Johnson took to his personal Facebook account Wednesday to post an angry and misogynistic rant about an unnamed woman, who apparently really got under his skin at the gym. According to Johnson, he took and threw the woman's yoga mat in anger, made her cry and threatened to do it again if she decided to "get in my way or any other athlete way again."

Johnson also warned her not to "run your mouth at me again," because "you won't win that battle I will," in addition to insulting her appearance with ugly and abusive language. The post was deleted soon after it went up.

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It is unclear what actually happened during this exchange, but the Facebook post was an especially bad look for Johnson, who has a domestic violence conviction on his record.

He defended himself on Twitter saying, in part, that he hadn't told the whole story.

The UFC said it was looking into the whole story.

"UFC is aware of the situation involving Anthony Johnson. We take these matters seriously and have commenced a formal investigation by a third-party law firm. We will act accordingly once we gather more information," the organization told FOX Sports through an emailed statement

Johnson issued an apology on his Facebook page. "I'm man enough to admit when I'm wrong and yesterday I was absolutely wrong," he wrote.