Feeling confused about my emotions

Hi, I am going to become a first time Gran imminently!
Me and my Daughter are extremely close, always have been. She's not lived at home now for a few years but lives close by so we see each other regularly and speak and text daily. Her partner has always been part of the family and welcomed.
Prior to her becoming pregnant we discovered that he had been having a long term affair. Nothing to do with their relationship just an easy ego boost and excitement for him.
Obviously she was devastated and it killed me to see her in so much pain and self doubt. I looked after her every day but never gave an opinion on what she should do.
His family kept a wide berth and said very little.
She decided to take him back, they were all very grateful and happy obv and for a while she was in control, he agreed to lots of changes etc.
She got pregnant quite quickly and it wasn't planned altho the baby is much loved and wanted.
His family have made her pregnancy miserable, almost like they are trying to "knock her down a peg or two"
They have been mean and aggressive both in person and by text. Told lies to create drama between my daughter and their son etc. She's been heartbroken very often, I've kept out of it, I've not challenged him or them to try to maintain the peace but it's been very hard!
He said I couldnt be at the birth, even tho my daughter wanted me to. Now I can but with "rules" on when I can go, what I can do and when I have to leave.
His family are now being super nice acting like nothing has happened and expecting her to do the same. And altho it's preferable to them being vile it grates on me!
I don't like how it's making me feel, I'm not a horrible person but I feel angry and jealous!
I feel like they don't deserve to have her or the baby they have given her so much pain.
She's going ahead with things to keep the peace and I think because she's just too tired to fight back!
It's almost like they are in control again now and I feel sidelined. Yet I feel ashamed of myself too, because they are also going to be grandparents!