The house next door to us has been made into bedsits for adults with learning disabilities. There are autistic people, people with DS, and others whose exact dx I have no idea of - all sorts, in other words.
They have a live in carer, and other carers and therapists visit every day. In the summer, they dig out the barbecue and all congregate outside having fun. Sometimes, they all troop down to the local coffee shop and spend a few hours hanging out there.
Basically, they all seem to get on together OK, are known in the town, have pretty good sociial times. I am not privy to their lives but they all seem to lead fairly normal lives. Some have jobs, some don't.
My cousin has DS. He lives in sheltered hosing and works on a farm a few train stops away. He is nearly 50 and is independent of his family, but of course they are around for him if he wtants/needs them. In fact, I shall be holidaying with him and some of is siblings and their families later in the year. They do look after him, but he has space to do his own thing.
Try to help your dd to become as independent as possible. She can have a great life.
As for counselling, I think that's a great idea and will make a big difference to hiw you view things and how strong you feel. I have found counselling very helpful in just helping me pull apart the twisted threads in my life, and seeing a clear way through.