Greene said the row with Nike left him "deeply hurt".
Greene had been signed to the sportswear giant for ten years before the deal came to an end in May this year. He has since been signed in what is believed to be the biggest deal for a track star rival firm adidas has ever secured.
Said Greene: "I wanted a couple of things put in my contract and I was shocked when Nike wouldn't agree.
"I had been with them a long, long time and it was more than just a company, it was a friendship thing. I thought I meant something to them.
"I was more than shocked, I was deeply hurt, very deeply hurt. It really got to me, it upset me.
"It got to a point when I was training that I thought 'why should I go even one step further? Why should I push myself when they don't care about me?' "
Greene was speaking prior to taking part in the Norwich Union Grand Prix in London on Friday.
