Your employer sounds stupid, stupid, stupid!
With a nursing shortage and no one lining up to do home health care (at least not here), why on earth would they get rid of someone because of their documentation skills???
Slow documentation never killed a patient, for G'ds sake!
If you were as good as you say you are, and I believe you must be, or you wouldn't say it...why didn't they invest the time and effort in helping you "get with the program" vs. firing you? Do you have any recourse? Like up here in Canada, there is such a thing as "wrongful dismissal" and an employer would be in deep s--t financially and otherwise if the court decided you were not given enough coaching, support, etc. that you needed to do your job. Maybe you could see if there is such a thing and if it is worth pursuing. It might help restore your dignity.
Take care of yourself. You know that if you don't, the bipolar stuff will raise its ugly head. Don't get stuck in the trap of self blame or beating yourself up. Life's too short; they were the morons, not you. Just remind yourself how much your patients liked you and what good care you gave. That's the most important thing at the end of the day.
It's like being knocked down. You are a little worse for wear, but you have to get up again and get back into things that are good for you.
Work is filled with enough struggles, inside and outside of us. Add more than the usual (like your charting) and that is a set-up for disaster!
Maybe they have done you a favour. Just hold onto your self-esteem; no one can take that away.
<sending you a very sympathetic hug>