He told the Reading Evening Post: "It was my fault - I made the decision to go to Stoke, no-one made me and it was probably the worst footballing decision I have made.
"That Reading team probably had two or three more years in it and it was a shame to see it break up prematurely.
"I felt it should have still been in the Premier League and I was angry that it wasn't.
"Everyone gets frustrated in their job, but rather than looking at what I had and what I could have achieved I chose not to be a part of that.
"I have played for Cambridge and Reading, not huge fashionable clubs and I thought going to Stoke might be a chance to help another unfashionable side do well.
"It was just not right for me. In hindsight it was a mistake."
Kitson never managed a goal at the Britannia and saw his chances of first team football diminish when Stoke brought in James Beattie.
He said: "What I needed was a club where I was wanted, which I already had, and a family which was happy, which I had.
"I threw all of that away for what I thought was going to be a new challenge. That was the wrong decision and that was my fault. I am just delighted to be back.
"I am frustrated I never got the chance to show what I could do. There were times when I wondered why I had been brought to the club, but that is in the past and now I can concentrate on getting Reading into the Premier League.
"I was more bemused there. I had been bought for a lot of money and wasn't sure I was being utilised in the way I thought I was going to be.
"You do have days when you wonder what you are doing. I played two games in left midfield and the majority of the others in centre midfield and it was difficult."