Yea. You need a lawyer ASAP.

There is zero chance the District is doing evictions in this cold weather. Even more so that it is over Christmas weekend.

The landlord is exposing themselves to some serious sanctions for this letter. They should know better and is probably hoping you won't push back. If they don't have a legal eviction notice -- which you would definitely know about -- then his threats could cause them serious trouble.

The bit about police is all bullshit. No officer will enforce this.

But you need to get in touch with OTA. If you can't do it tomorrow then do it Tuesday.