Chrisoula Workman filed the defamation and false light lawsuit Monday in Los Angeles. She has been accused of being emotionally abusive to Winter and temporarily lost custody of her daughter in October.
Winter is currently living with her adult sister Shanelle Gray.
The lawsuit names actor Matthew Borlenghi, a teacher at one of Gray's acting studios, as the defendant. It accuses him of falsely calling Workman an "abusive monster" in an online comment posted with a Los Angeles Times story last month.
Borlenghi says he hasn't yet seen the case but has seen comments from Workman that he says are fabricated.