The Ireland AM host had kept news of the split between herself and her husband David Ryan under wraps for the past five months.
The star issued a statement on Wednesday through agent Noel Kelly confirming that her marriage was over.
However, she has claimed she only made this move after an unknown individual contacted numerous newspapers informing them of the split.
The TV3 star took to her Twitter account yesterday -- and said "karma" will come back to haunt the person involved.
"To the charming individual who called the papers and told them of our marriage break down forcing us to go public, one word -- karma," she said.
Sinead, who married David in France in 2009, did not appear on Ireland AM yesterday morning, and was not expected by colleagues to come in.
Co-host Anna Daly took her place on the breakfast couch instead.
Her TV3 colleagues were believed to be unaware of the love split -- and there has been no speculation as to why they went their separate ways.
Yesterday, Sinead also took the time to thank friends and well-wishers for their messages of support.
"Thank you so, so much for all of your kind words and wishes, they are hugely appreciated and make a real difference. Thank you," she said.