Much like arguing with an A is useless, it sounds to me that trying to explain anything rational, healthy or otherwise sane to your parents is going to fall on deaf ears the way sane thoughts do on A's.
Think of your parents as having a disease like that of an A.
I started to do that with my own FOO and it made me a) much more willing to be around them when I had to be and b) much less disturbed by the quacking that is constantly spilling from their mouths.
Clearly we don't get involved with A's and stay longer than we know we should because we grew up with ideal role models, right?
Suki said this earlier Sadly, people can be toxic to us even if they are part of our family. and I'd wager to say that it's actually quite the case that our families more so than most others are the ones that are toxic.
Whatever lessons we learn growing up- starting very very young about whether it's okay to ask for what we need, to stand up for ourselves, to be "selfish" etc... get ingrained and are a part of our brains wiring. Only with lots of introspection and hard work (like you do and I do and most people who make it here do) are we able to start to see things more clearly and learn what's healthy for us. And there's bound to be pushback from those who aren't interested or able to join us on that self discovery journey.
Please please please know that your parents words and hurtful non support has NOTHING to do with you. It's their issue. You are doing what's healthy and it's clear to me that your parents aren't able or willing to see that, perhaps bc they themselves don't know what healthy looks like (that's what I tell myself about my own FOO)...
They don't know better (which is not an excuse at all) but much like an A can't see what's in front of them until THEY are ready to, your parents aren't going to suddenly "get it" and it seems to me that the more you interact with them the more distressing it is to you.
Do you have good friends you can turn to instead? I've slowly started to create my own non blood family and accepted that my FOO is not ever going to be that supportive, loving, healthy group of people I'd love us all to be. Rather than let it distress me, I try to accept it and have found "family" in other places.
I'm so sorry for all you're dealing with and I know all too well how much it hurts to not have the people who you'd think would be there for you most, not be there at all.
I'm sorry...