Your DD has blocked her, yes? I'm afraid she sounds very toxic. It's awful that she's going to be a mother, especially given the genetic link means she is more likely than average to have a child with a spectrum disorder of some sort herself. She doesn't sound like someone with the maturity, patience or self-awareness to cope, does she, to put it mildly.
OP I know this is easier said than done, but you have to just try to forget this and block her from your life and mind, at least for now. All of us have very finite resources, emotionally and in energy terms, and with a child with the sorts of needs ours do, you can't allow someone as much of a draining distress-causer as this young woman to occupy any of your brain space, or to take up any of your resilience. You need that for yourself and your child.
Sometimes people let you down very badly, and it doesn't really matter in the here and now whether she's broken, or just nasty, or some mixture. You have to just cut it dead and move on, so you don't drown. You have far, far more important things to worry about than her. Every time you get upset about this or allow her to distract your thoughts, she is stealing some of the inner resources your daughter needs, and is entitled to have, from you. Just drop it. Let it go. Seriously.
Again, 
for you. (And I knew what you meant, about the terminations. Wasn't offended in the least. We all have our own reasons for our choices, good, bad and a mixture of the two, and part of being a grown-up is accepting others may not like them.) And again, come over to SN chat. There are some very lovely, very accepting people there who have walked this path before. A lot of unconditional understanding and support is available.