You should have been told.
Autism deeply affects how we relate to others. I have it and wasn't diagnosed until I was 34. If I had known, I would have been able to interpret my problems differently rather than internalize them.
When I was a teenager I went through a rough time, just like you are right now. I had no idea why I couldn't really connect with people or why nobody liked me. I became really despondent and tried to take my life a few times.
Autism is a way of being. It isn't a disorder that needs to be repaired. It is a part of who you are.
Knowing, understanding and accepting your autistic traits will help you get through this, discover who you are and heal.