I don't really know, myself. I withdraw from things and shut down on occasion, but I don't depersonalize as such.

You said you just changed your medication. So I strongly suggest going immediately back to your prescriber and discussing it with them. It might be a side effect that you don't have to endure. They are supposed to be there for follow-up for precisely that reason.

I'm sorry to hear you're having such a tough time. Take care.