I'm sorry you've gotten the diagnosis. Is there any chance that instead of also having fibro, that the symptoms you've been experiencing all along are related to your having MS? It certainly would be easier to have to manage just one disease, than two.
At any rate, many of us here are on one or the other of the drugs now being prescribed for MS. Sandy described it pretty well: since MS is a progressive disease, and since any flare or exacerbation or progression (not all progression is apparent through experiencing a flare!) can lead to increased disability,
I do whatever I can, to slow the course of the disease. I've had MS for nearly 24 years, now. I've been on Betaseron for the last 12 (it only came on the market about 15 years ago).
Sure, sticking yourself with a needle is never comfortable. There are lots of folks who will help you learn how to do it, and over time, it becomes routine. The side effects of the interferon-based medicines (Rebif, Avonex, Betaseron) can be unpleasant, but are manageable. Copaxone has some side effects, too, but again, they're manageable.
The GOOD news is that there is a choice! You can start with one, and if it really becomes too difficult, you can switch to another. You can study the materials and decide whether you want to deal with one injection a week, or every other day, or daily, how the different requirements of the meds might fit into your lifestyle (some require refrigeration, others don't), whether you'll need assistance to inject (and how comfortable your helper will be with the various kinds of injections -- muscular, or under the skin).
And again...if one doesn't seem comfortable for you, there's a choice. Not that many years ago, there was no viable treatment for MS at all.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....