Matthew Stafford's wife says she has NO REASON to apologize after selling her tickets to tonight's "Monday Night Football" game ... saying she bought 'em herself and has a right to get her money back. 

Kelly Stafford has been under fire on social media after posting 5 tickets to the Lions vs. Saints game on StubHub ... with critics pointing out that her Detroit Lions QB hubby has reportedly made close to $100 MILLION and she should've given the tickets away to fans.

But Kelly hit back on Instagram -- saying, "I bought those New Orleans tickets to take my family to the game, but found out at the beginning of this week my grandfather is very ill so I am going home to see him instead."

"I'm also sorry for being HUMAN and wanting to sell the tickets we purchased because we are not able to go."

"We do a lot for this community and I'm beyond tired of getting badgered for this ... get over yourselves."

Kelly was selling some of the tickets for $200 each. Sure, she has the right to sell the tickets if she wants ... but was the $1,000 really worth the bad publicity?