My salary has increased and now she's so disabled she cant work and is asking the court for life time support.
She seems to function in every other life activity fine .... So how debilitating can fibro be?
I know and get this situation you're in, so I can empathize that you want it to be fair.
Generally: As said, fibro can be severely debilitating so that it is not possible to work at all, and it can be moderately debilitating so that it might be possible to work a bit, but it's a tough condition however severe it is.
Me in comparison: I worked even longer hours than she did, before. I had small signs the 10 years before, certain pain flares and stiffness, but nothing that would question working, then it suddenly really flared up, shortly before covid. I had to stop working for 10 months to get healthy enough to work at all, and even then could only work 10h/wk. Working from home during lockdown in my job doubled my stress and again caused a big 3 month flare. Then it was the jabs that kicked me out totally, so I can only do 5-10h online now, cos luckily I don't have as much brain fog as others do. If people see me for a few minutes, they can think I'm "fine", often I can carry really heavy things, or in the first 1-2 years I could sometimes cycle almost as fast as I used to. But that lasts for about 10' and if I push thru and override pain, that can debilitate me for hours, weeks or months. I can play table tennis for 20'-30', and on good days win, which looks "fine" on the surface, but then I need a long break.
Your case: It is well possible that she seems to function in every other life activity, whilst she can only function for several hours, by pushing thru, and then ends up not able to move for days. Forced to work too much, this would end up in big crashes, perhaps a total crash. Working from home or even more so getting long covid from a covid bout or the jabs can also have been the last straw or even the cause. A diagnosis of fibro may be part of several co-morbidities or be a sign of other conditions which can all be severely debilitating. (In my case it's MCAS, which fibro and maybe some kind of ME/CFS may be part of.) So it's not necessarily about fibro, i.e. the precise diagnosis, it's how capable someone is of moving, tolerating stress, sleeping, thinking clearly enough etc. which may all be very limited.
Another part is however, that whilst fibro is usually a life-long condition, it can worsen with age, co-morbidities etc., but also with de-conditioning and not finding things to do against it, it can also get a little better by pacing, avoiding triggers (like work stress). This will be just as individual as the severity, so might need to be checked at intervals to see how it's changing.
Me on the receiving end: I've long considered maybe being able to commute again. But despite finding many small things that help me I've given up hope of that for the time being, due to increased co-morbidities. So I'll have to go on disability for at least a year or two, even if that means considerably less money. Being able to work also depends on how stressful the working environment is, and mine has got considerably more stressful due to not being able to phone any more and an unfavourable boss change.
, in answer to your question of how debilitating can fibro be = EXTREMELY (I know with some of my really bad flaire up's its left me in bed for day's!) I can't really speak for your wife (and her fibro) as I'm not in her body and her level/pain/fatigue (and capacity to do things) may be different to mine, but i can't imagine a 45 minute daily commute would've been very comfortable for her, (i hope your day is well) 
(this law "could" be used by manipulative people this makes me sad) I don't like this law
