Has TIM MCGRAW been hiding a 'secret son' from wife FAITH HILL?  According to 'The National Enquirer,' 23-year-old Tyler Zarbo is NOT Tim's biological child, he's actually the son of Tim's former fiancée, Kristine Donahue.

National Enquirer/Facebook

Tim has been supporting Tyler, although it's not clear how, but he hasn't told ANYONE about it, including his wife FAITH HILL. Tim LEFT Kristine FOR Faith back in the mid '90s. Faith and Tim were married in 1996.

For some reason, the 'Enquirer' is also painting Faith as insanely jealous. A source said

'Every time Tim glances at another woman, Faith jumps all over him. She's never forgotten Tim broke up with another woman to be with her, and she's worried that he could do it again . . . to her.'

Apparently, back when they got married, Tim promised Faith he would never lie to her, and he doesn't. Instead, he just withholds the truth. (--Which is still lying.) The source said, '[Tim] doesn't tell her everything. He keeps some secrets to keep the peace.'

At least the 'Enquirer' did talk to Tyler. He said,

'Tim McGraw was like a father to me when I was growing up. He saw me as the son he never had, and we've stayed in contact. I wish he could have remained as my substitute dad, but it just wasn't meant to be.'

As you'd expect, as soon as this story got out, Tim's people issued a statement to People Magazine:

'The 'National Enquirer' story is full of inaccuracies and misrepresentations about Tim and Faith. We aren't going to comment on false statements that appear to have been sensationalized for the purpose of selling tabloid magazines.'

The rep isn't denying Tim's relationship with Tyler. It sounds to me like the 'inaccuracies' and 'misrepresentation' are the parts that show Faith in a bad light.