I am sorry that you are having such a torrid time.
You have an awful lot on your plate at the moment - dealing with the current effects of active MS, dealing with the implications of that (everyone thinks that they are going to be one of the lucky ones whose MS is fairly quiet, and it is a heck of a blow to find out that this is not so) and now having the business of treatment options (also alarming) to think about, plus you are JC+, which is not what a person wants to hear when she is considering starting Tysabri. That’s a heck of a witch’s brew. No wonder you are feeling it.
One worry to cross off your list right now is the fear of anyone holding it against you if you decided against Tysabri. There are plenty of people who refuse it irrespective of JC virus status, and some who come off it when they turn out to be JC+, even when they have been doing well on it. No one thinks any the less of them.
The thing to concentrate on, I think, is making sure that you plan your consultation and get your neurologist’s answers to those questions that you have raised. To your list I would add, ‘What extra steps will you be taking, given my JC+ status, to monitor my health?’ He/she will probably talk to you about the particular level of risk that your blood test indicates - the current, more sensitive, tests will give a lot more useful information than just + or -. So don’t panic about the + bit. These days a person can be just a little bit +, with a risk not much greater than a negative person. It isn’t like a pregnancy test anymore, when you either are or you aren’t. And, as you probably know, the risks during the first couple of years of treatment are low for pretty much everyone.
Your best resource is information, and your neurologist is the best source of that. No one can give you certainty, and it is always a matter of playing the percentages. But the more hard information you have, the better the chance of your decision being a well-founded one. One thing I would say is, do give proper weight to the risks of MS. You can’t opt out of those! And your experience so far has given you a flavour of what poorly-managed, aggressive RRMS can do to a person. Remember that there are no risk-free options available, alas.
For my part, I have been on Tysabri for nearly 3 years now, and no relapses. Years ago, my JC virus test came back negative, but the newer tests are revealing that plenty of people who looked negative then were actually low positive all along, so I do not set much store by that. For me, it has been little short of a miracle. MS had taken plenty of lumps out of me by the time I started, and that disability is permanent, but there has been nothing big and new, and that has just been amazing. Quite honestly, I would have tried anything, JC virus or not. I am glad to have had the opportunity.
Good luck with whatever you decide.