Ex Bukit Batok MP David Ong had sent out typed letter of apology to residents of his former ward.
The letters worded in the 4 official languages, English, Chinese, Malay and Tamil, were circulating on social media on April 7.
"I had publicly apologised to Bukit Batok residents in my letter of resignation on March 12, and in my subsequent apologies through the media. However, I have also wanted to write this personal letter to each of you."
Mr Ong had resigned over a "personal indiscretion" - over an affair with a married grassroots member.
"I am grateful to all those who have stood by me during the recent difficulties, especially my wife and family".