Nic Cage's ex claims her rental house is infested with toxic black mold that makes her sick -- and tells TMZ that's why she stopped paying rent ... and got slapped with an eviction notice.
We broke the story ... Christina Fulton and her son Weston Cage's landlord claims they missed two months worth of rent -- totaling $12,000 -- but now Christina's saying they weren't even living in the house because the mold problem was killing her.
She says she had a company test the house ... and claims they found dangerously high levels of mold.
Fulton says she has allergies that make her susceptible to illness from mold -- so she informed the landlord about the problem, withheld rent and temporarily moved out ... until it could be fixed.
Fulton claims she and the landlord have now worked out an agreement -- she'll start paying rent again once she has proof the mold is gone.
We don't know if the landlord's backed off the eviction -- we've reached out, but so far no word back.