That is interesting to me: Why did your life "fall apart" after receiving the diagnosis? AS is lifelong and your problems should have been exactly the same before as after.
Did people start treating you differently? Did you lose access to assistance or accommodations? Did you change your opinion of yourself?
Think back about what you've learned about disability through your cultural upbringing: Things like, disabled people are useless, disabled people can't have talents, disabled people can't work, disability is obvious and severe all the time, etc. Look at those face-on and question them thoroughly. Ask yourself whether they really apply to you. Did you start to think badly of yourself because you were labeled with a disability and thought that all that stuff now magically applies to you, when it didn't before?
Okay, so you suck at math. Plenty of people suck at math. Plenty of people suck at writing. Plenty of people have ADHD. You're not alone and you're not the first person to face this problem; people before you have solved it. It needn't take over your life. There is nothing wrong with having autism, nothing wrong with having a disability. Disability is a normal part of the human experience. What, you thought life was supposed to be easy? It's not. Not for us, not for NTs; not for anybody. But it is worth it.