As someone who is disabled I'm not offended by MrsS. Through out my health getting worse, I've experienced a pattern of behaviour from friends / family etc that show a lot of people can't cope with it.
They'll be friends / gather facts / then comes the we're going to cure you with vinegar and honey stage / when they realise you can't be cured they go distant.
OP hasn't really said what kind of disability it is, I think that would help as disability covers a wide spectrum of issues. Look at the Paralympics.
I guess I'm lucky that as I've been ill most my life my family have made sure to focus on me as a person, over my defined by disability. That is a big thing, people let the disability be all defining if that makes sense.
As a guy if the child was school age I would wonder why OP didn't do something during the day as employment law supports carers, so in a way, you could forgive a guy for thinking OP could possibly do something, even if voluntary.
It does really depend on the disability.
I'm a big believer of if you're meant to be you'll be.