My neuro doesn't think MS really shortens your life span at all, since all the new medications can really decrease your progression.
Anyway, when I was first diagnosed 6 years ago, all I could think about were negative thoughts and also about dying. It took awhile, but I finally realized that you shouldn't waste your time worrying about dying from MS, you need to think instead about LIVING with MS. And I do mean LIVING! Even when I have flare ups, I do everything I can to make sure it doesn't interfere with getting on with my life.
For example, I am currently blind in my left eye from probable optic neuritis caused by my MS. However, although I am very hopeful my eyesight will return, I only took a few days off from work, then found alternate transportation so I could get back to my life. I have since taught myself how to drive one-eyed (don't come at me on my left! LOL) and have been on 2 trips with my husband.
What I'm trying to say is, do all the research, keep up on new things, and visit this board and others when you need support, but don't let worrying about MS and the future consume your life. Live your life and work MS in only when you have to.
BTW, I've also been in counseling for about 5 years - that helps alot too!