Because MS gets its feelers into every aspect of life - health, family, relationships, work, money, duties and commitments, future planning etc etc - it can sometimes feel that the problems are coming at us from all directions. It does sound a bit as though you are having one of those moments; I really feel for you. It is filtered word scary, as you say.
Might it help to think in terms of identifying the things that are (potentially) easiest to fix? (If you have been through this a million times - and I am sure that you have! - my apologies for trying to teach granny…) If you can get a handle on the fixable things, that frees up some thinking space for finding the best way to manage what isn’t fixable. Getting to the root cause of the back pain would be a good start. As I expect you have found already, having MS can make it particularly difficult to pin down what is neurological and what isn’t. Specialist doctors are notoriously bad at communicating across specialism boundaries. But time and patience (yours) spent on getting to the bottom of it could be time well spent.
The only other thing I would say is that your wife has her own road to travel when coming to terms with your dx. A very, very common reaction from loved ones is for them to pretend that all is well and it is all right really. Another common reaction is to catastrophize and rush around tearing hair out and wailing that their spouse is going to be an invalid in a fortnight and you will all be out on the streets and boiling up gravel for soup. At least you are spared that one, by the sound of it, so be thankful for small mercies! (Sometimes, confusingly, it can alternate between the two, so you’re not out of the woods yet…) Seriously, though, it is very usual for people with MS to feel that their spouse is playing things down - if only for their own psychological protection - and that can leave a person feeling very unsupported by the very person whose support matters most. Just give it tims and try not to let it hurt you. This is difficult stuff for everyone. It does not mean that she doesn’t believe you - more likely that she just wishes it were not true (as do you, of course).
Good luck with the MS nurse. Will you be discussing disease modifying treatments? I hope so. You should also be able to get advice on medication to help with the symptoms you have already, if you have had no joy from the GP. Most GPs are not very clued up about MS, and they do not all go to much trouble to remedy that. I hope you have a good GP - they are a real blessing for a person with MS. You might well need to chase up appointments and keep gently chivvying away if things are taking too long. Patience is not a virtue when trying to extract appointments from the NHS.