Former England skipper Vaughan believes that Pietersen may face a fight to improve his relationships with his teammates and that the batsman could be receiving bad advice from his representatives.
Vaughan told BBC Radio 5 Live: "If it's true that he sent those texts, it will take a long time for him to be allowed back.
"I don't think he's getting the right advice. I don't know who is advising him but in my eyes they are not doing the right job for Kevin.
"It's been a mad, but also a very sad week for the England cricket team. There are no real winners, but one very big loser and that's Kevin Pietersen."
The third Test begins at Lord's on Thursday morning.