This doesn't read so much as a hot take and more like a cry for help. I'm sorry to hear that you have been having a hard time with your son. Any divorce is difficult, and having a child with special needs certainly doesn't make it easier.
I of course don't know the whole situation, but based on what you've written here, I would reccommend two things. First, at your next sessions with your son's therapist, you might ask her if she knows, or has information on where to find, someone who can help you with parenting and divorce from your perspective. It's important to remember that the therapist is always on your side, and you need not be embarrassed to ask her about such things.
Second, I think it might be valuable to search for other autistic parents and/or children in your area so you can share experiences and tips. Your son might also appreciate meeting children who are more like him, especially later on. Perhaps you can find parenting groups online, or you might ask the therapist about this as well.
Whatever you choose to do, I wish you a lot of strength and success.