Here we are strangerthanfiction I'm very interested in your experience as the effect on ds2 is something I worry about.
Balancing the 2 is very difficult at times, they have very different needs. My friend with an autistic dd has and NT about the same age as ds2- we meet up a lot and in the future we hope that they'll be able to talk to each other about the awful things to do with having an autistic sibling.
DS1 is very passive though. Far too passive. He tends to ignore ds2 rather than be mean to him. DS2 adores ds1 and is constantly in his face- so he does cope very well (ds1 I mean).
For ds2 I think the hardest things really are when we are out and about. We can't have normal family days out (as I'm sure you will know). And I think this is something about autism that makes it a particularly difficult condition to live with. So much of family life has to be on the autistic child's terms.
I used to worry a lot about that until a friend pointed out that she can't do much as a family as her eldest dd is 12 years older than her youngest 2. And they therefore have different needs. That made me feel better.
I do try to do things with ds2 by himself. For example we couldn't take ds1 to the cinema but as ds1 will be in school full time from September I'll take ds2 then. Also mum has sad she'll have ds for the day sometimes so we can take ds2 to places we couldn't go with ds1.
It must have been awful for your mother being at the end of the refrgerator mother period. I guess it was before any of the sensory stuff was known either- which would have made it a truly baffling condition. I do find it easier to cope with when I understand why ds1 is behaving the way he is.