College lecturer Marie Penman claimed that her complaints against senior figures in Kirkcaldy were taken no further.
Ms Penman, 48, said she first put in a complaint in June 2014, which was acknowledged by Tasmina Ahmed Sheikh MP, who was the party’s women’s officer at the time.
Ms Penman claimed ex-deputy chief executive and former MSP Shirley-Anne Somerville, and current SNP chief executive Peter Murrell – husband of party leader Nicola Sturgeon – was also made aware of the situation.
Ms Penman said: “I thought when I was elected as an SNP councillor in January 2015, the situation might improve but, if anything, it got worse.
“The Kirkcaldy branch of the SNP was split down the middle and became a bitterly divided group, full of hatred and recriminations.
“The Kirkcaldy SNP Facebook page at that time was shut down by SNP HQ, due to the many intimidating, slanderous and threatening messages being posted on it.
“As convenor of the branch, I tried to keep things calm, but the situation became intolerable, and in June 2015, I resigned as convenor.”
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Ms Penman said she sent the SNP a detailed timeline, listing bullying that had occurred since June 2014.
Despite this, she said that she was not made aware that any action had taken place.
Since Ms Penman’s resignation, seven other officer bearers in the branch have resigned, which she claims is mainly due to “the bitter in-fighting” that took place.
Ms Penman claimed that in Kirkcaldy the SNP membership is around 1,400, but that only 30 party members attend the branch meetings.
She said she will carry out the rest of her term as an independent candidate.
“The people who voted for me in the by-election last year may feel disappointed that I am no longer representing the party they voted for,” she said.
“However, in all conscience, I simply cannot belong to a party that allows aggressive, bullying behaviour to go unchallenged. I asked for help and support from SNP HQ on numerous occasions, but was ignored.
An SNP spokesman said last night: “We’re sorry that Marie struggled to feel at home within the SNP, but wish her all the best for the future.”