He tried to stay stoic, but Mr Singh broke down more than once while addressing the media in Shimla.
He said his main concern was that he was not informed personally about the decision to sack him.
'I received a call this morning from the president of the BJP that I should absent myself from the meeting, because he said tempers were running high or words to that effect. I told him that I will go back to Delhi, but he said 'don't go back I will call you'.
The BJP says he has been expelled because his book released on Monday glorifies the Quaid and criticises Sardar Patel for the 1947 partition.
'I thought this book would set Pakistan on fire. But it is troubling India,' Mr Singh said.
'I have committed no sin...none whatsoever...against India.'
After this, he broke down in tears, and then paused to collect himself.
NDTV said that BJP leader Lal Kishan Advani supported the decision to sack Mr Singh. Mr Advani himself created controversy when, four years ago, he described Mr Jinnah as a secular leader.
Mr Singh said he sent a copy in English and Hindi to Mr Advani and said 'There ought not to be selectivity when discussing dissent.'
Reacting to that, BJP leader Ravi Shankar Prasad said 'L. K. Advani's case is different. Advani never said Sardal Patel was responsible for partition. Jaswant Singh defied the party constitution and core.'
In Gujarat, Chief Minister Narendra Modi's government on Wednesday banned the book alleging it defamed the image of Vallabhai Patel.