I'm so sorry!
But don't do any big decisions about Beeper, sometimes things like this happens, it doesn't mean that Beeper is mean, sometimes it's just in their nature.
The best thing you can do for your flock at the moment is to get another budgie ASAP.
Beeper has already gone after Weeble 3 times before the incident where she bit her toe off. Unfortunately we don't have the space to keep her in a separate room away from the remaining flock. She has a history of being aggressive to birds the whole time she's been here. Trying to manage it has really affected the quality of life for her and Weeble because they don't get enough out time. It's a decision I should have made some time ago. She spends most of her time watching/stalking Weeble and posturing at her. I'm not willing to take any more chances at this point. I don't think the animosity between the two of them will ever ease up and I don't want Bongo to have to be around her after watching her kill his mate. I don't blame her for going after Beans when she got on her cage or even in it if she did that on her own. I know that was her instinctive behavior. I also firmly believe she would try to kill any of them if she were the one to get out. Maybe she would be fine with a different species or sex, I really don't know. It's mostly about the quality of life concerning all of them. Beeper is a great bird on her own and deserves her own person/people. That's really all she wants. She really likes humans quite a bit. We gave it a good try over the last three and a half years after we couldn't locate her family and decided she could stay but she still hates Weeble and I don't think that will ever change. It's been over two years since the last fight with her and Weeble and it's just sucked since then. To let her out all the others have to be covered and her and Weeble just scream nonstop and the out time isn't enjoyable for anyone. I cover her when Weeble comes out and it's the same thing.I agree with J.T...Beeper did not maliciously kill Beans. They react from instinct. It just is what it is. Beepers is not capable of discerning. Animals live in the moment... In Beepers world all Bean was is an intruder in his space, simple as that.