I have been depressed since I learned that my 2 year old has been diagnosed with autism. Does it get better?

If You Mean the.... Autism, with proper medically proven therapy, many children show tremendous improvement to the point where total mainstreaming occurs. Unfortunately not always. But the earlier you begin, the better the odds.
Yes. I can speak to this as a parent as well as a physician since I have an 18 year old with autism. It is not easy, and you will have a lot of highs and lows. Seek out a local support group who can help you access resources. Set high expectations and never give up.
Yes. As with any grief reactions things will get better you do need to take the time to grieve the loss of "normalcy" as you dreamed it for your child. If necessary, see a grief counselor to help. Autism support groups can also help parents cope.
Take care. Yes, it is very common for family members, especially parents, to become sad and depressed and feel helpless when their child is diagnosed with things like autism. It is very important to get in touch with other families and support groups, as others can help you feel less overwhelmed. You are not alone. There are people who can help and give advice from their personal experience. Good luck.
Therapy. For you and your daughter, an excellent psychotherapist and supplementations with the following: drinking only alkaline water, no red meat, no soda and eat more fruits and vegetables daily. Theses supplemtations eliminate the toxic by-products of what you eat. Log on to: www.Drernie.Co.Cc.