MJ's Nephew Taj Jackson -- I Was Molested as a Child ... and Michael Helped Me Cope

Michael Jackson's nephew Taj Jackson -- Tito's son -- just revealed he was molested by a family member on his mom's side when he was a kid ... and says Michael personally consoled him after the incident.

Taj dropped the bombshell on Twitter this morning during a tirade aimed at MJ accuser Wade Robson.

During the tweet session, Taj claimed he's in a unique position to judge Robson's sexual abuse allegations because he knows what it's like to have gone through such a traumatic experience.

"That is how I KNOW Wade is lying. Because I AM a survivor," Taj tweeted. Followed by: "I was sexually abuse (sic). By [a family member] on my mom's side of the family when I was a kid."

As for Michael, Taj says MJ "was a support system for me and my mom" during his abuse ordeal ... he even tweeted a picture of a note he says MJ wrote to his mother. The scrawl reads:

"Dee Dee please read this article about child molestation and please read it to Taj (and his siblings) ... it brings out how even your own relatives can be molesters of children, even uncles or aunts molesting nephews or nieces. Please Read. Love MJ."

And Taj makes it clear -- he thinks Robson is LYING for CASH.