Laois county councillor Caroline Dwane Stanley has announced her resignation from Sinn Fein, citing how the party dealt with a controversy surrounding her husband Brian Stanley.
Ms Dwane Stanley said she had made the decision after “careful consideration and reflection”.
The party responded by saying the decision had not been unexpected.
Former Sinn Fein TD Brian Stanley quit the party in October amid a controversy relating to a complaint against him.
He claimed he was subjected to a “character assassination” by a clique within the party and likened its processes to a kangaroo court.
Sinn Fein rejected his claims and insisted it handled the matter in accordance with proper procedures.
In a social media post on Friday his wife said she had now followed her husband out of the party.
She said: “During my 27 years of membership, I worked diligently to advance the objectives of the party.
“I met and worked with some great republicans on that journey and will always cherish those memories.
“I have given this careful consideration and reflection over the recent past and decided to resign my membership of Sinn Fein.”
Ms Dwane Stanley claimed since the controversy surrounding her husband, she and her family had endured “outright attacks”.
She added: “I had hoped that the party at leadership level would have made the effort to engage with me directly and give some support and assistance to me to try and deal with these matters.
“However, no contact has been made by the leadership with me over the past five months.”
She said she would continue as an independent republican councillor.
Ms Dwane Stanley had been Sinn Fein’s only councillor on Laois County Council.
A Sinn Fein spokesperson said: “Coun Caroline Dwane Stanley this evening tendered her resignation from the party.
“This decision was not unexpected.”