I went through a period of mourning for myself, my lost opportunities, my wasted unhappiness. I read around the subject, discussed it with a very few trusted people, and gradually come to terms with my new view of myself.
The first thing that changed for the better, oddly enough, was my ability to go shopping. I no longer felt like an embarrassment to myself when I found a shopping environment overwhelming. I accepted that, and, instead of powering through with self-hatred and distress, changed how I dealt with it. For example I might choose to go at a quieter time, or I might enter the shop with my head down, check out the floor, raise my view a bit, check out the stand nearest me, glance around a little to widen my view, eventually look over the stands (I don't know why, but it's all the gubbins hanging from the ceiling that particularly bothers me), and only when I felt steady actually start walking through the shop.
I found myself forgiving my parents for not solving the problems of my childhood. I realised that they had been doing the beast they could with the knowledge and understanding of their times, just as I am with my dc. It was a personal forgiveness, I didn't say anything to them about that, but it freed me from a lot of anger that I had been carrying around.
Eventually I realised that, actually, I had done pretty well with myself. I had not achieved to my academic ability, but I had had good jobs, married a nice man, had children who were doing well.
Around this time I also did CBT for my depression. Two courses of that, together with ADs, at the right time for me to accept my autism, really changed my world view. Of course I am still autistic, but I have learned to accept myself, to enjoy my individuality, to not fear 'getting it wrong' when I'm with other people, to embrace my differences.
Someone said to me a few days ago, "you're kind and you're quirky" and it felt good.