turd in the punchbowl

so a beta who was reading my manuscript today told me that I should cut the 1st 150 pages and that she wasn't connecting emotionally with my MC. I about shit. seriously. this was the first time I had ever gotten a crit like that. not from the agents who have read it or super editor so I was a bit put out. it got to me big time. I know my betas are supposed to be honest but she was the first who basically said it sucked. just about everyone has found stuff that they liked but she said it was a turd in the punchbowl. I disagree. I know there are flaws and I'm working to fix them with super editor. cutting the first 150 pages has never been suggested or hinted at. that's almost a third of the ms and would leave gaping holes which the beta suggested that I trade for the characters and action in the last half. my minor cosmetic surgeries that I have been performing under super editors direction apparently needed to be amputations of the nuclear level.
deep breath...it's just one beta. don't over react. my vampires are fine. what would Alan Rickman do?