EXCLUSIVEJason Kidd has an unlikely ally in his feud with Mark Cuban -- his arch-nemesis ex-wife Joumana ... who tells TMZ the former Mavs superstar DESERVES to have his jersey retired in Dallas ... no matter how much Mark hates his guts.
The Kidd vs. Cuban feud kicked into high gear this week when the Mavs owner told the media he would NEVER retire JK's jersey in Dallas because he was upset at the way Kidd left the team back in July.
We figured the statement would be music to the ears of Joumana Kidd ... since she went through a NASTY split with Jason back in 2007 ... the kind of divorce that makes Tom and Katie's split look downright friendly.
But Joumana tells TMZ ... that just ain't the case ... and despite her rocky relationship with Jason, she believes the 39-year-old -- who played a key role on the Mavs 2011 championship team -- should be treated like the hoops hero he is.
"[Jason] is an amazing basketball player I can never take that away from him. He’s one of the best guards to ever play in the league. “
She adds, "Lots of fans would love to see his jersey retired in Dallas ... I believe he’s earned it and he deserves that based on what he did for the Mavericks.”
Cuban suggested he might change his mind over time ... if he does, Jason might have to send a thank-you note to his ex.