Wow - you are in a tough place right now.
It sounds like three distinct issues here:
1. Family illness and where you feel your responsibility lies
which is threatening your
2. Business and financial security
which is likely triggering
3. Your current depressive episode
I think the first thing you need to do is try to take that shower. I'm hoping that's where you are now since you've logged off just recently. That will usually make me feel at least a little more human and able to function.
Now, you need to call a business attorney. Find out what your financial rights are and if you can lock down the financial access to the business accounts. Also determine whether or not she can be held personally liable for those charges. It is your father's business - do you have the majority share or are you equal partners? Again, a lawyer can help you sort all that out. Call the bank too, just to see if you can have the cards locked down - explain to them what is happening.
Call your pdoc. See if you can add a PRN for anxiety or something to get you through this. Maybe make an extra appointment with your therapist if you're seeing one. Be sure to do what you need to do to take care of yourself.
As for the family issues - first, there is only so much latitude one can give to a family member who refuses to tend to their illness. If this had been the first manic episode in years or if she'd never done anything like this before, that might be different. But it's not. She's done this before, and pretty recently. It sounds like she may never have fully come down from the last manic episode. This is not your responsibility. It is hers. And if she's incapacitated and can't stop the mania, then her husband needs to step in and have her hospitalized, against her will if necessary. This may be a conversation you need to have with him. Since it's a fairly recent diagnosis, he may not understand what his legal rights are and what to do in case of an emergency, which this is. I understand that you're fairly new at managing this too, and don't mean to put the pressure on you, but it sounds like you have a much better handle on this bipolar thing than she does and can help her husband understand. I don't quite understand why you are concerned about having to take her kids - can't her husband keep them? Or are they children from a previous relationship? Still, I don't see why the kids wouldn't live with her husband. You've got enough to worry about without adding things like that.
Most of all....breathe.