The former corporate banking chief told an inquiry he was directed to grow his division by group chief executive Andy Hornby in the run-up to the crash.
Mr Cummings, the only ex- banker to be fined and banned from the City, told the Parliamentary Commission on Banking Standards: "It is unfair, and it is also seems a bit sinister.
"We are not the only failed bank. There are at least four or five of them, and I find it curious that I was singled out.
"So someone, somewhere decided that that was the appropriate action to be taken."
After Lloyds TSB's rescue takeover of HBOS, the combined Lloyds Banking Group took billions of pounds of writedowns on loans made by the Edinburgh-based bank.
This included what the commission estimates was a £26 billion hit from lending made by the corporate lending division Mr Cummings headed from 2006.
Lloyds required a £20bn bailout from the taxpayer.
Mr Cummings was subsequently fined £500,000 by the Financial Services Authority (FSA) and banned for life, the only banker to face such discipline.
Giving evidence in private to the Parliamentary Commission on Banking Standards at his home near Glasgow, due to ill health, Mr Cummings revealed the FSA had initially intended to fine him £1m, then cut it to £800,000 before coming up with the final sum on condition he did not take his case to a judicial tribunal. Mr Cummings said he rejected using the tribunal because he could not afford the legal fees and was not fit enough.
Mr Cummings, who first joined Bank of Scotland in 1973, told the Commission: "If I lived my life again, I would never take the chief executive's job."
He added: "Would I like to be born again and live a life different to the one I've got? The short answer is yes."
In a transcript of the session on November 27, which was published yesterday, he admitted that the bank's loan book had got out of control.
And he said that when HBOS set out its plan for 2006-2010 he was directed by Mr Hornby and finance director Phil Hodkinson, now chairman of HM Revenue & Customs' ethics committee, to keep increasing the targets for the division for each year.
In particular, Mr Cummings said he was not happy about targets to grow by 35% in 2007 to make up for the underperformance of the retail division, then led by Benny Higgins, now boss of Edinburgh-based Tesco Bank.
"The 2007 profits were forced," he said.
But he said he did not complain to the HBOS board. "I did not go and bleat to them," he said.
He added that Mr Hornby, now chief executive of bookmaker Coral, was also occasionally involved in approving large loans.
However, Mr Cummings refused to blame any individual at HBOS. "I am absolutely heartbroken about what happened, and I live with it every day, but it would be inappropriate of me to point the finger at any colleague," he said.
Mr Cummings insisted he was not a "control freak" at HBOS. He added: "Every day I look in the mirror and ask: What did I do wrong?"
However, he was scathing of his treatment by the FSA and said: "It was like living in an American soap opera.
"I find it bewildering, bizarre and downright impossible to believe this country has an organisation that is out of control to the extent that it is. I think it is unacceptable behaviour."