Step on it once maybe...but repeatedly...c'mon man!

TMZ.com:

Chad Johnson headbutted ex-wife Evelyn Lozada so hard during their infamous domestic dispute last year, she was left with a massive bloody gash on her forehead -- and TMZ has obtained photographic evidence. The photos were taken by Davie Police in the Florida emergency room where Evelyn was transported following Chad's attack on August 11th, 2012.

SEE THE PHOTOS HERE! PUTS A NEW PERSPECTIVE ON WHAT WENT DOWN!

According to police, the forehead laceration measured 3 inches. TMZ broke the story ... Johnson was arrested for domestic violence shortly after the explosive argument at his Jupiter, FL mansion. Evelyn filed for divorce three days later. Following the arrest, Chad pled "no contest" to the domestic violence charge and was sentenced to 12 months probation and domestic violence classes.

Chad was thrown back in the slammer last week after slapping his lawyer's backside during a sentencing hearing. He was released again yesterday following a probation violation sentencing hearing. During the hearing, the judge called the head gash photos "horrific."

See her response here