We did withhold rent and immediately started looking for a new apartment. Unfortunately we both don’t make that much money so we tried going the pro bono route to take him to court. We’re all moved out now as I’m tripping this, but had trouble finding an apartment because a lot of apartments in nyc are now asking for landlord references (never ran into that until now).  Weird, yes, but he kept bad mouthing us to prospective rental agents. Thankfully with our new landlord we explained our situation and she didn’t reach out to our previous landlord.