Ince, who is currently the boss of Blackpool, has also claimed that football will not see a character in the mould of Ferguson again.
"I'm totally shocked. What he's done in unbelievable. You'll never see anyone of his kind again," Ince told Sky Sports News.
"Two weeks ago he was talking about staying on for another two years, so it's a massive, massive shock. The way he treated me was like a son."
Ferguson will officially step down at the end of the season.