I am so devastated and yet a bit relieved. I know I have always been considered an odd ball and am horrible in social situations but after and evaluation I got my results today and I have autism 
Oh my, I'm sure it's good to find out. I know Autism is a developmental disorder, causing issues with communication and interaction in social situations, but not much more about it. Have you treatment plans?
Well, I am enrolled in therapy and I am looking forward to that but am also a bit scared. They told me I have Classic Autism. Treatment is necessary as Autism is not something that is curable. 
Well at least there is treatment available. I know some of the risk factors can vary, such as a family history, genetic conditions and older parents. Do you know if that came into play?
You know what, I have a cousin who is Autistic but she has Asperger's Syndrome which is also a form of autism. 
Did you ever notice any symptoms with your cousin? Such as repetitive patterns in her behavior and activities, or problems with interaction or communication?
Her symptoms are very noticeable so it was not difficult for them to get her diagnosed, but with me I think my symptoms were a bit more subtle. My mom feels guilty because she said in retrospect I always avoided eye contact and loved to be alone and would freak out if even minor changes were made around me
Yes, I know that often with Asperger's the person will appear to be a bit more clumsy and their language skills not the same as others, so I'm sure that was a strong indication if your cousin had these symptoms. But, it can be hard to diagnose, so mom shouldn't feel guilty.