I'm sorry if this has been said already. When it comes to many people on the spectrum, they may understand what the problem is but struggle with understanding how someone else is feeling about it and putting themselves in their shoes. They REALLY don't get it.

Any response you give is an invitation. What's best for you is to block her, change your number and email address, and really commit to putting an end to any connections and conversations.

Her parents will always be her parents and they understand. She's limited, lacks understanding, and they love her deeply. One of the hardest things in life (IMO) is to raise a child with special needs. I won't go into details about that.. but it's likely the only way they know how to help her is to forgive. They, too, need to firm up on their boundaries because lessons always begin in the home.

I really feel for you. There's NOTHING you can say to have her understand. Don't engage, 100%. Take care of you and move forward. As you've said, she's a child.