Seems Chad Johnson fully understands the consequences of his actions -- saying his 2012 domestic violence arrest didn't just ruin his NFL career ... it also destroyed his legacy. 

The former Cincinnati Bengals wide receiver went to Twitter this morning and in an obvious reference to the incident with then-wife Evelyn Lozada wrote, "3 seconds of anger cost me a lifetimes worth of work."

He continued, "I LOVE everything in sight for a reason, those few seconds I stopped doing so." 

After Johnson's arrest, he was immediately cut from the Miami Dolphins and was essentially blacklisted from the NFL.

Johnson is now playing ball in Canada ... but it's clear he believes his arrest overshadows his achievements on the gridiron. 

Chad then tweeted ... "Now that was a #TBT"