I don't think you're BU, I pick up from your posts that you're worried about your Mum too.
I would seek some support from DS Association, Social Services and Local Carers support.
My son is 31, I'm 57...I'm suffering carer fatigue (the care for him has included 10 years of caring for elderly DM and PIL).
My son goes to a day centre four days a week, he enjoys hates it, mostly, but NEVER wants to go, every morning is a battle.
He has severe LD, austism, mobility problems and multiple health problems.
Whilst I was caring for my mother, I was forced through circumstance to push him towards occasional overnight respite (he was always so heartbroken at the suggestion, so previously I had just let him get his own way it go).
It was the best thing I ever did, he loves to go.
They are totally geared up to support him and I am able to recharge my batteries stay sane.
I worry about the future, he has an older brother but I would never want him to be his carer.
I see him living in supported accommodation within the next 5-10 years. A number of his peers from the day centre already do so.
I am lucky he has a good care co-ordinator from Social Services and our local SS is pretty good with Adult Learning Disability support.
There are days after days after days where I feel totally ground down even though I love him with all of my heart.
I hate to go out with him, it's so exhausting, he can be so challenging and I am worn out.
Then there are days where he makes me laugh till I cry, my heart burst when I see his kindness and compassion for animals, babies and little, old me women.
So I plod on. 