AF, posting before reading entire thread. Apologies for any resultant faux pas.
Your poor friend seems to be in a very similar bind to my own after splitting with Twunt Two, and you know what horrific damage that shit wrought on my mental, financial & social health. Instead of a straight split, we entered into an absurdly complicated agreement that involved renovating two flats, ending up with one each. He stayed in the one we'd been doing together (and was liveable), while I bought a cheaper one that needed a complete internal rebuild.
It dragged on for ever. The finances became ever more complicated and I was utterly ground down by the strain of living in a shell of a place, doing building work every night, going to work in the day (had to shower at the office as no hot water in flat) and being constantly baffled by Twunt. I completely lost track of the money, where we were at with the agreement, and why I felt so angry about it. Every time I got him to sit down with my spreadsheets, he proved I was wrong ... you get the picture.
I had 2 breakdowns & lost my job. My finances became more & more pickled. I took out extra loans. He only ended this absurd agreement when his new fiancee insisted. He ripped me off royally, and I am certain he gained a great deal of satisfaction from his control over me.
During that time, I was seeing therapists who kept saying they felt I should get out of the agreement - but I felt utterly trapped in it. Nobody helped me de-confuse the figures. Friends tried to help me out with money, bless them, but it all sank in The Project and I'm sorry to say I still don't know where it went. It was a lot of money.
I sought professional advice from several sources. The advice I received was atrocious! I'm STILL finding out what bad advice I was given, and how much further along my recovery I'd be now, had I been well advised
I haven't read enough to know exactly what your friend's problems are, but here's some (good!) advice:
Sit down with her for a couple of days, going through her finances with a nit-comb. If you're not the person to do this, find someone. When I met Twunt, I was quite the financial wizard. By the time my flat was due for repossession (yes, just as I finished the work), I had absolutely no idea where the money - and my power tools! - had gone, nor why I didn't know. That part was the worst. I hired people to help me. They didn't.
I have only just found out - last Friday, in fact - that I should have been advised to apply for bankruptcy BEFORE my credit ran out. In complete opposition to the advice I received from the CCCS and various solicitors, I should have ignored all correspondence & requests for information from creditors, and refused to consider IVAs. Apparently (I now know) this is the correct advice if you owe more than £15,000 and have little left to lose.
First and foremost, keep her alive. She's been to the doc and got meds, which is good. If she son't go for talking therapies, get her to start journalling. Sketching is also good - I used to buy those pretty books with nice art paper in them for my diaries, and draw in them as well.
Take her out for nice meals, get her round for pizza & a DVD, that kind of thing.
If she's lost control of everyday things, go round with another pal and do all her housework.
GET THE NUMBERS SORTED. When the picture is crystal clear, go through it with her in your own special, no-nonsense way.
Get an appointment with a CAB money/debt advisor (though I got bad advice from one of them, the CAB is also where I got the good advice on Friday.)
Make sure she knows that letting go is often the only sane & viable option. You can let go of far more than you thought (in every sense) and find life becomes more manageable as the 'stuff' goes.
Good luck! Hope at least some of that was useful; will read your thread properly in the morning