I can't begin to imagine how you are feeling, either, but I felt shock, horror and more than a little sadness when I read your story. So whatever emotions you are going through right now is ok.
I do suspect that your parents are feeling more than a little sorry for what they did. It was clearly meant to split you and Neil up but it had the opposite effect and they must realise now that they have lost your love and respect. Have you tried asking them why they did it? I suspect it would be incredibly painful to ask but it may give you more understanding, even if you can't forgive them.
But I wonder if you are grieving for more than just your daughter? You also lost your parents at the same time. You didn't speak to them for 7 years and now your relationship is strained. It must have felt like being orphaned. These people, who were supposed to love and protect you, also took away your dignity, your freedom of choice and forced you to have a dangerous procedure against your will. No-wonder you are angry and upset.
I can't help you to feel better, only you can do that, but talking helps and we are all listening.