Mourinho harshly criticised one of his players after a match against Sassuolo in November 2022.
Mourinho believed that the team was betrayed by the attitude of an unprofessional player. It turned out that the Portuguese was referring to Karsdorp .
The 29-year-old broke his contract at the end of last summer and is now with PSV.
"Mourinho never apologised. He is not that kind of man. I noticed that he tried to restore our bond, but I kept him at a distance," Karsdorp told NU.nl.
"He called me a traitor about eight times in the dressing room. I can take it, that's okay, but he should never have done it in public. I blame him for that."
Karsdorp believes that there were no problems with Mourinho before that.
"We used to get along, we were close, so I was surprised by his actions. He went too far. After that dispute, I really should have left," he added.