I am really sorry that (probably) your worst fear is about to be confirmed - but Bob is right, I think (though it pains me to admit it!) - when you know that you are sick, it is better to finally have a label so that you can make informed decisions regarding your care and have access to any treatments available. It will take a bit of time for you to get your head around this, and you have some time before you see your Neuro, so you won't have to spend the whole of that first valuable visit in a numb haze of disbelief and shock - you can go there fully informed and ask whatever needs to be asked (Dom is also right, and again it pains me to admit it!).
I think that you are blessed to have a great GP who is prepared to tell you what the Neuro letters say (most would avoid that unpleasant task)- maybe a meeting with him/her is called for and he/she can help you come up with the questions you need to ask.
I know how you feel - I (and my Neuro, funnily enough) clung to the possibility of ADEM as a diagnosis for me following my first definite clinical event and MRI. Then my LP results came back and I had another relapse, then another, and we had to accept that it was ms. Strangely though, at that time my symptoms gradually cleared up and my ms was so mild for the first 6 or so years, that I didn't need to consider the CRAB or any other drug or treatment options. Then things went downhill in a big way and didn't get much better (for me anyway), so I went on Avonex - I have had some progression (possibly elements of SPMS?), but apart from some concern of a relapse at the moment, I have again been pretty stable. I say this to establish that things don't always immediately get worse after diagnosis...
I would want to know the details of my scans and test results - what type of ms they think it is, what the available treatment options are for that condition, what to do in an 'emergency' i.e. if/when you have another relapse (if you have RRMS) - do you just go to the casualty department, or call the neuro, or call your GP for the IV steroids? Can they make a stab at your prognosis (based on stats)...Also, what can they prescribe for any other symptoms you have - such as pain, muscle spasms, vertigo etc - who does your scripts, how often, when do you see the neuro again...so many questions
Shit - go back to my 'Best Advice' above - much more sensible and coherent!
All the best and if you need to chat some more, we are here for you.