I feel for you, almost brought some tears to my eye.
People stop taking meds for a variety of reasons....
She might have stopped taking her meds because she didn't like the side effects.
She might have thought "I'm cured", so stopped.
Maybe they were too expensive.
Maybe the meds really weren't helping so she figured why bother.
Maybe her illness took over and convinced her she didn't need the meds.
It is probably ESPECIALLY hard for her to realize she is sick because of her experience as a mental health professional. She used to help "those people", and now she is "one of them". Can you imagine how that would be to believe?
Also, mental illness is a CRUSHING diagnosis. You don't WANT to believe it. It's almost like someone telling you that you've got AIDS.
How long will it take for her to snap out of her psychosis? Unfortunately, that is next to impossible to presume. Hopefully not long!
Should you visit her? YES! Even if she doesn't want you there and acts like a jerk to you, it is not good for ANYONE to be isolated, especially those with mental illness. From what you said she is not interacting with the other patients or staff, so she really really needs someone to talk to...again, even if she goes out of her way to let you know she doesn't want you there, she probably really does. Imagine a little girl that lies and says "I don't like you! Go away!" but you know that really she thinks you're cute and she loves you, she just doesn't wanna admit it because boys are icky

How can you help her? Well, you're off to a good start. Study the illness. Don't constantly argue with her and be like "OK mom, that's not happening, the government is not controlling your thoughts with a machine", that will just set her off...but at the same time, don't "buy in" to her delusions...try to ground her in reality about topics she is comfortable with..maybe she likes shopping, talk to her about the new store that opened at the mall...this will help encourage the "normal" side of her. Love her as much as possible, be nice to the staff and the other patients...don't be scared. and PRAY PRAY PRAY!
Hope this helps.