I haven't been through what you've been through to be sure. I can at least relate in some way to the dismissive and infantilizing things people respond with to people dealing with neurodivergence, mental health, etc
There's this book on grief by Megan Devine that has a chapter called "the second half of the sentence." It talks about how when people respond to our pain with platitudes or dismissing how it has affected us, it's because there's a second half of the sentence they're not saying.
"You're so starting" so you'll be fine.
"They're in a better place" so don't feel so bad.
"Other people have it worse" so stop complaining.
"Everything happens for a reason" so don't get upset about it.
Even in relationships where their intent isn't to be dismissive or malicious doesn't mean it isn't. It distant mean it's doesn't hurt.
It doesn't give them a pass.
It's not like knowing this makes it easier to deal with, but it has helped me be able to explain why those responses are toxic. It also doesn't mean that everyone will choose to change instead of becoming defensive and denying it when this is explained. It's has made me more aware when reacting to other people's pain. And it's made me treasure more the people who "get it."
If they won't say it, I will:
I'm sorry you have to deal with suffering from their words on top of all the pain you're already experiencing. It's messed up, and you shouldn't have to be in this place.