The Brazil international has completed a big-money move to France just weeks after penning a new deal at Giuseppe Meazza.
Milan had looked to tie him down on fresh terms in an effort to fend off mounting interest from afar.
They were, however, unable to turn down the riches offered by PSG and Silva will be turning out in Ligue 1 next season.
“I was happy with the transfer and sad about my exit from Milan because I experienced some strong emotions there,” said the 27-year-old centre-half.
“This is football, one day you are here, the next day you are somewhere else. I had signed a new deal with them a week before.
“People call me a mercenary, which leaves me upset. I am not making more money at PSG. This is not my fault, I would like to apologise to the fans.
“This was a difficult situation for me, I did not want to leave Milan, and neither did my family. But it was a positive thing because Leonardo and Carlo Ancelotti called me. When I joined Milan, it had also been Leonardo to call me. I really like him.
“PSG are a dream club, like (Zlatan) Ibrahimovic said.”