The axe came just over a week before the former St Mirren and Sunderland boss was due to lead his team out in the Hampden showpiece against Celtic - the second cup final appearance of his two-year tenure.
“It was a sore one to take," Ross told the Scottish Sun.
“I thought I had done enough to have more credit in the bank.
“When you go through a difficult run of results you suffer as a manager anyway.
“But I was sacked when I felt we had done a good job for two years, so it felt sore.
“I’m not bitter about it. That’s not the type of person I am.
“But the truth is I felt an injustice about it all and it definitely stung.
“The timing of it exacerbated things for me too. To be sacked before the cup final, I felt was extremely harsh."
Ross also revealed that he has maintained dialogue with Martin Boyle since his departure amid reports that Saudi Arabian side Al-Faisaly are preparing another offer for the Australia international.
With a huge salary on offer, the ex-Hibs boss revealed that he has encouraged Boyle to pursue the “life-changing” move.
He said: “I have spoken to Martin a few times in the last week.
“He’s one of the Hibs players I’m close with and he’s asked me for my advice on his situation.
“He has an opportunity that simply doesn’t come around very often. The one he has in front of him is genuinely life-changing.
“This is a player who has had to graft the hard way throughout his career. He’s worked his way through the levels and had to deal with some serious injuries along the way.
“He would be deserving of a big money move.
“But selfishly, as someone who knows him really well, I hope he gets the chance to grab that opportunity."