I agree, she has every reason to be angry with them. But I hadn't realized how angry Cat still was with her Mom, and like you, I thought Anniversary was when she came to terms with Vanessa's involvement in Beasts projects. I was, however, a bit confused about all this bottled up anger. A very dear friend of mine mentioned a comment somewhere, which kind of cleared up my confusion. I think, for me at least, it all goes back to how Cat was written in Season 2. She forgave Gabe, who tried to kill not only her and Vincent, but all of them essentially, but not her Mom, who was actually a good person and had good intentions. Not only did she forgive him, but also she dated him (I still cringe at the thought of them together). They messed up her character last season by having her date Gabe (while she could have any other guy, including my personal favorite, the shrink dude from season 1). Regardless of how "lost" she was, that was just the most implausible plot.
Anyway, going back to her parents, I think Bob's & Vanessa's past and them working for Muirfield would have been a very interesting plot to explore. Oh well..
I don't think Cat had resolved her feelings about her mother. She said she was conflicted. I think she was still disappointed that her mother had so many secrets and that she didn't really know her as well as she thought she did. I think she put it all on the back burner in season 2 because Muirfield was gone and everything appeared to have turned out alright. When her aunts came, she was obviously anxious because she knew they would make the whole bridal shower about her mother. And they did. It felt more like a wake. They wanted to invite her dead mother's spirit to the shower and were going on about what a wonderful, caring person she was and how she looked after sick children. Yes, children that were being experimented on like Gabe. She then went on to experiment on soldiers like Vincent. She did alot of harm at the end of the day and I think I would be conflicted about her if she was my mother. I think Cat was just sick of hearing all about all the good 'Saint Vanessa' had done and wanted to shed some light on the harm she had done too. I think it was completely understandable for her to explode like she did.
What you said here, plus all the bad things that continued to happen. Father was murdered, finding out her mom never told her about Bob, finding out Bio Dad was also involved and trying to kill Vincent, finishing Gabe off but then finding out there's still more experiments out there.
Here's something they could have a conversation about -- Vanessa's serum may have ruined Vincent's life, but what if being a beast kept him from being killed in Afghanistan? In On Thin Ice, Vincent mentioned the "first time" he was shot which would imply that he managed to get shot more than once in an 8 month period, actually less when you consider he would have been in basic training for the first 2 1/2 months.
And I wonder if Heather knows that their dad was killed because of Muirfield