The Argentina international became the Premier League's most expensive import in history when signed for nearly £60 million from Real Madrid last year, although he was a costly flop.
Despite starting well, with three goals and six assists from his first 10 games as a United player, a nagging hamstring injury and subsequent drastic loss of form saw him fall out of favour under Louis van Gaal and the club opted to cut their losses on the midfielder, who has moved to Paris for €63m (£44.3m).
"First, you must know that Manchester United wanted to sell me," the former Real Madrid man told the press.
"It is a shared decision between the three parties. They wanted to sell me. I also wanted to leave and PSG wanted me.
"But I am very happy be here. Manchester is the past."
PSG dominated in France last season, winning Ligue 1, the Coupe de France and Coupe de la Ligue.
An assault on the Champions League is next on the menu for the capital club and Di Maria hopes that he can assist the likes of Zlatan Ibrahimovic in making them a continental force.
"The club have been trying to recruit me for several years," he explained. "It is a great source of pride to come here and play with such important players like Ibra, [Javier] Pastore, [Marco] Verratti, David Luiz.
"All have the objective of winning the Champions League; it is also mine."
