Councillor Caroline Dwane Stanley, the wife of former Sinn Féin TD Brian Stanley, has resigned from the party with immediate effect.
Ms Dwane Stanley was the party's only councillor on Laois County Council.
Her husband, Independent TD Brian Stanley, who previously chaired the Oireachtas Public Accounts Committee, left Sinn Féin in October following a bitter dispute.
In a statement on her Facebook page on Friday night, Ms Dwane Stanley said she had given “careful consideration and reflection over the recent past” in regard to her decision to resign her membership of Sinn Féin.
“Given how the party leadership dealt with the controversy that arose in July and related matters since then including outright attacks on both me personally and my family by some local party members, I have come to the conclusion that Laois Sinn Féin is not a safe place to be.
“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 Sinn Féin leadership over the past five months, she added.
The Laois councillor said that while the party has always prided itself on the values of equality and in particular supports for women in politics, "in my case this has proven to be a fallacy".
“With this in mind I have decided that the time is right for me to draw a line on 2024 and resign, look to the future and embrace what I hope will be a better political future in the time ahead."
She said she will continue in her role as an independent republican councillor "providing vigorous and effective representation for the Portlaoise/Abbeyleix Municipal District".
In October, Brian Stanley resigned from Sinn Féin, launching a scathing attack on a probe into him by the party.
In July, a complaint had been lodged with Sinn Féin from a "longstanding member" about the Laois-Offaly TD.
He claimed that in recent months "a certain clique within the party have gone to extreme lengths” to damage his reputation and character.
At the time, he said: "Given what has transpired and the work of my legal team, what is very clear is this process lacked objectivity, was seriously flawed and was devoid of impartiality.
“This ‘inquiry’ has been shown to have lacked any shred of credibility, not least due to a significant abuse of process. In many ways it resembled a type of kangaroo court. Legal examination of this matter will continue."