Schwaner, who is married to Botany MP Jami-Lee Ross, has told the Herald leaving the board was the "most honourable" thing she could do as she had no confidence in Collings' leadership.
In her resignation letter, Schwaner alleged that under the chairmanship of Collings in the past term the board had become a "toxic environment".
At the time Collings said Schwaner's decision was "disappointing" and a surprise given they both stood on the Vision and Voice ticket.
In response to her allegations, he said: "I'm not going to lower myself to that level. I've got the support of the community and I've got support from the board."
He denied a culture existed of attacking council staff.