Welcome to the board, Nicole.
In the early days of a diagnosis, life can seem even MORE overwhelming than it was before when you were just dealing with abnormal behaviors that you maybe thought was partly your own doing (I think ALL of us felt that at one point or another in the early days of our parenting journey), or something your child would outgrow, or some other explanation that probably tried to minimize and normalize what you were experiencing. When we finally find out that yes, in fact, our child is different and that there is a name for it, we start the grieving process because now the reality of the situation hits us squarely in the gut and we must now abandon the preconceived future we had all planned out for our kid.
Unless our friends or extended familiy have a child like ours, it is very hard for them to relate, much less sympathize with our situation. That leads to further alienation.
SLSH gives good advice to you. You have to nurture yourself or you will crash and burn out quickly -- and your kids need you to be up for the challenge as their parent and their advocate. They can't get through this challenging childhood on their own.
Seeking out support groups like this one, or a face-to-face group, or even private counseling for yourself is a MUST. You also need to read, read, read and educate yourself on all the aspects of your child's situation: medications, therapies, educational and social supports, the whole ball of wax. Ask questions: of teachers, doctors, therapists, others who have been-there-done-that, and if you aren't satisfied with the answers, go to someone else and keep asking until you understand.
Eventually you will feel that you have some control over the situation, some understanding, and you will have a good idea of what is possible for your child and what to expect. It may not be what you originally envisioned the day you brought that baby home, but it will be a path that you can help them travel in the best way possible.
If you haven't checked them out already these are some good websites for additional information and local chapter support:
http://www.thebalancedmind.org/
http://www.CHADD.org
http://www.NAMI.org