Oblomov Oh good lord, no, I'm not at all talking about parents struggling or making mistakes - whether children have SN or not, and whether the parents are depressed or not.
As TheRealSmithfield said on that other thread, "You see this is where the crossover happens. The point at which a parent who made mistakes becomes toxic is when they continue to blame the child for their own behaviour."
That's a theme repeated on this thread. Sometimes the first mistake isn't even that big a deal - obviously i'm not talking about abuse - but huge damage is still done by parents' denials and refusal to recognise the impact of their actions, even on the occasions they acknowledge the facts.
This is why I'm not worried about Hobbgoblin's DD. Sounds like life has been hard for everyone, especially yourself Hobbgoblin (hope meds, etc continue to help), but you're desperately aware of the impact on others and want above all else to ameliorate it. So you're not saying things like, "It didn't happen; you shouldn't have been bothered by it; it was your fault." Your narrative, however you actually express it, is "Mummy was grumpy. It wasn't your fault. Mummy's sorry." You are in no way taking your DC's love and forgiveness for granted - so she will almost certainly give them freely! (And although as you say she will probably not remember, if she ever brings it up when she's much older, you'll be able to acknowledge her experience - not try to sweep it under the carpet.)
The problem with the OP on that other thread is that every time she even slightly approached acknowledging her actions, she coupled it with But-it-was-his-fault-not-mine. HE WAS TWO! And as people kept pointing out, "Sorry but" is not an apology.
I have to say, there was a lot else about her behaviour that waved big red warning flags for me: accusing other posters of cruelty to her, seeking "help" at the moment her DS was about to move out and out of her control, continually reminding him of money spent on his treatment, her threats to leave her DH because he doesn't take her side, and lots more. Some of these may be neutral in isolation: together they were... interesting.
Oblomov you said, "They are abusive parents blaming a child when the child has done nothing wrong.
But that is a slightly different situation, when you have a SN child."
Did you mean to use a word like "wrong"? Or did you mean something like exhausting and extremely challenging for the parent, like a continually screaming baby? Because there's such a gulf between despair because you fully accept your responsibilities but have no notion how to cope or strength left to do so; and sitting down coldly 24 years later and writing, "I continue to remind him of his bad behaviour from aged 2- 18. His response is that he was a child and couldn't be responsible. That is where we disagree."