De Bruyne's Man City exit 'so difficult' for Guardiola
Belgian midfielder De Bruyne will leave City when his contract expires at the end of the season after Guardiola decided not to offer him a new deal.
The 33-year-old this week revealed his disappointment at not being given an extension to his 10-year spell with City.
De Bruyne has been hampered by a series of debilitating injuries over the last two years, costing him significant playing time and reducing his effectiveness on his return to action.
He joins a growing list of City stalwarts who have moved on in recent years after the likes of Yaya Toure, Sergio Aguero, Fernandinho, David Silva and Vincent Kompany.
Even so, saying farewell to the influential De Bruyne will rank among Guardiola's most painful goodbyes.
"I have lived a lot of things with them, a lot, good moments and terrible, bad moments," he said.
"Sergio, David Silva, all the players - we can make a long, long list and we are only nine years here.
"There are a lot of players that come in and after they leave, they are part of my life. It's impossible not to feel it. Of course, it's so difficult.
"The feelings that he (Kevin) has, I understand completely. It cannot be otherwise. I wish personally for him and his family all the best."
De Bruyne is one of the most decorated players in the club's history with 16 trophies, including six Premier League titles and the Champions League.
He can take a step towards a third FA Cup when City face Nottingham Forest in the semi-finals at Wembley on Sunday.
Winning the FA Cup and helping City qualify for the Champions League after a turbulent season would be a memorable way for De Bruyne to bow out.
"That would be good, of course it would be. He's behaved unbelievably all these years and, this month, again, since he announced that he's in the last months here in Manchester City. It will happen until the end," Guardiola said.
"He's trained really good. He's playing and helping us with his skills and his talents. I know he wants the best for the club."