Hi guesgirl, and welcome to PC.
I know what you mean about being the "glue" that holds everything else together. That has been me for a while. If there's one thing I've learned, it's that I need to keep myself healthy first. Sort of like when they tell you to put on your own oxygen mask first in an airplane. I saw from your other post that you have a therapist - that's fantastic. It's a huge step that is difficult for some people to get to - so, in that regard, you are already ahead and in the right direction.
I know what you mean about the diagnosis being scary. But, on the other hand, knowledge is power. Now that you are closer to understanding what is going on, you are closer to a solution. You are still the same person, but now you have the opportunity to heal and become an even better person by getting the roller coaster of moods under control. As for telling other people right now, that's probably not necessary. As long as you, your husband, and your therapist are all on board with your treatment, you are not alone. That, and now you have us!
There is a lot of good information on PC about bipolar, and a ton of fabulous people here to lean on. Another site you might want to look into, if you haven't already is
www.bipolar.about.com . Bipolar disorder isn't the end of the world. Take a look at the about.com site - you'll find, among a ton of other things, a list of famous people with bipolar disorder. Many of them were/are very successful people, with everything from actors, writers, politicians, astronauts, scientists - lots of creative and influential minds. It may not feel like it right now, but you are in good company.

You're going to be okay. One day at a time, okay?