It is illegal under CA law AB291 Immigrant Tenant Protection Act to intimidate a tenant out of their unit by using their status against them.
Under this law, it is also illegal:
– to threaten to report tenants to immigration authorities, whether in retaliation for engaging in legally-protected activities or to influence them to vacate;
– to disclose information related to tenants’ immigration status;
– For lawyers to ask questions about tenants’ immigration status in discovery or at trial;
– For lawyers to report, or threaten to report, the immigration status of persons involved in housing cases.

Here’s what you can do:
1) Write a letter describing the threats and asking the landlord to stop immediately.
2) Talk to an immigration attorney and create an emergency plan.
3) If problem continues, consult a non profit that specializes in housing. You may need to start a legal case against the landlord.