Terry played in Petrov's charity match at Celtic Park on Saturday and hit the post from just inside his own half as the Stiliyan XI beat a Celtic XI 5-3 in front of a sell-out crowd.
Chelsea captain Terry is often the victim of abuse from fans but Petrov said that they are not seeing his real side.
"He doesnt always have an easy time with the fans, but I have seen a very different man to that image," Petrov told the Mirror.
"He has gone out of his way to encourage me at different times – always sending messages and texts while I was going through treatment, even though sometimes it might have been a month before I felt strong enough to return them."
Petrov, who is in remission from acute leukaemia, thanked the Celtic fans after playing in the charity match and was almost reduced to tears in the 19th minute (the shirt number he used to wear) when the whole ground rose to applaud him.
"You've made today special for me, my family and for all these players. Thank you very much" – he announced to the crowd.
The match had an emotional finish as the entire stadium stayed behind to sing "You'll Never Walk Alone."
"I said I wouldn't cry but I couldn't hold it. It was an absolute privilege," Petrov told BT Sport
"It is just great. I nearly started crying (in the 19th minute) but I held it. I was in a dark place a year-and-a-half ago.
"They have always been brilliant to me. It's been amazing. Today I'm here with all these friends and the Celtic family. It's incredible."
Petrov's former Bulgarian international team-mate Dimitar Berbatov scored a hat-trick in match that also contained the likes of Robert Pires, Paul Lambert, Neil Lennon, Jamie Redknapp, Gareth Barry and Henrik Larsson as well as celebrities such as comedian John Bishop and One Direction's Louis Tomlinson.