I think the issue is that OP has allowed the last 3 years to be dominated by her daughter’s stated desire to go to university. She has done whatever is required to ensure her DD had the opportunity available to her because that was what her daughter said she wanted. Of course, OP may have wanted that too and be disappointed because that was also her goal for her DD- but I suspect OP has given everything to enable her DS to reach her goal, to be told that really it isn’t what she wants after all. Not that I think her DD should go to university if she isn’t ready, or do a course that she doesn’t feel is for her- if course she shouldn’t. But it is tough for OP too. I doubt she actually hates her daughter.
I think it does depend on how much this has been driven by her DD’s demands and how much by OP’s hopes for her to go to university. I have a cousin who had significant anxiety- she used her anxiety to control her immediate family to quite some degree (not intentionally, for the most part, I think). She too needed quiet to study and would become anxious about not being able to study well if the house was noisy and this would lead to becoming anxious about a particular piece of work or exam, which would then become a vicious cycle of ever escalating anxiousness (sometimes so anxious she could not attend, for example). In general, she was anxious about not being able to get onto a particular course with quite high minimum grade requirements, as this was her goal. She would say this was the only career she wanted and would be “a failure” if she didn’t get to do this. So she then worried excessively about noise/studying/not getting good enough grades etc that this impaired her ability to study. So everything revolved around “being quiet so x can study” or “not stressing A out as then she won’t be able concentrate to do x”. Precisely because her parents really wanted to help her achieve her goals, despite the anxiety problems, they tended to pander and try to create conditions that were conducive to her feeling calm- even when that meant everyone else tiptoeing around her or not being able to do as they liked, for fear of setting off her anxiety. She did have counselling and CBT too, which helped a little. I have long suspected that there are some autistic traits there, but to my knowledge thus has never been diagnosed (and I am not an expert). TBH, I do suspect she was aware she could use her anxiety to get her own way at times, and I do think she was selfish at times too. I think my aunt and uncle were unwise to let her anxiety dominate their family’s life in the way they did, and I know the relationship with her siblings are quite strained. There is a lot of resentment towards their parents too, it’s quite sad really.
So, the upshot if that long story is that I can see how the anxiety issue could breed a situation where OP pulls out all the stops to help her DD reach her goals because she desperately wants to help her DD reach her dreams, to not let the anxiety impact her future too much and to want to try and keep open doors that she worries the anxiety may close for her DD. Partly because that’s what parents want to do, partly because that’s what her DD has told her she wants to do. Then when her DD turns round and says “actually, despite all that effort, expense and pandering to my whims, i’ve decided that I really don’t to go to university after all”, I imagine it feels like a rather large slap in the face. So OP probably is angry that her DD has changed her mind at the last minute after (presumably) being adamant that she wanted to do this course- to the point where OP did everything possible to help her achieve her dreams, including putting her DD’s needs above the rest of the family at times.
With hindsight, OP could probably reflect that she should not have done all of those things- but if she had not tried to do all these things to help/support/enable her DD and then her DD had not achieved the grades/place on this university course there is every possibility OP may feel that she had let her daughter down. Or, equally likely, that her daughter would think/say that her mum hadn’t helped enough, given how much she was struggling due to her anxiety. And if she had, the outcome would have been different.