On the Fred matter, I don't really see what else he was supposed to do? Everyone between the Well and L.A would have been killed if he did choose Fred. So thats what? a good chunk of England, all of Wales and Ireland and 48 out of the 50 United States of America. You're going on nearly 400 million people dead just for Fred?
That's my point exactly. If the fate of the entire world were at stake, then Angel would, however reluctantly, kill Buffy, all of her friends, and all of her army of Slayers. Activating that many girls at one time would almost certainly have a tremendous overload effect, just as bringing Buffy back from the grave did, only several thousand times worse. If you imagine one Slayer as a single light bulb in an electrical circuit as an example, it would work something like this: One light (Buffy) shines with no problem The circuit was set up to handle one light. Add a second light to the circuit, (Faith) and there is still no problem. The built in safety factor would allow for such an overload. Carry that analogy further, however, increase the circuit's load by a factor of, not 100%, but instead something on the order of 20,000% or more, and the circuit self delf destructs, burning the house (or planet, or even the entire universe) down.
If bringing back Buffy upset the Continuum enough to allow the First Evil to activate and command, not just an army of Bringers and a super powered general to lead them, but also a second army of ubervamps, just think of how many demons 2000 plus Slayers must have allowed access to our reality. Remember what Anya said in Season 2 about all of the demons left here are only the halfbreeds, and that all of the REAL demons, far more powerful and vicious, were expelled long before mankind took control of the planet? Assume that the First Evil was the one single Old One allowed to remain here, but carefully restrained in the hellmouth with its powers greatly limited. Maybe there has to be a balance of one true demon to one Slayer, since the Slayer's power comes directly from that demon. Doubling the stress by allowing both Buffy and Faith strains the restraint, but it can still function properly, at least for as long as Buffy was likely to live. Having her die and return, however, would create a surge in the cosmic forces that weakened the hellmouth seal enough for the FE to influence our reality, but not interact here directly.
Now, assume that Angel somehow learns that, because of the Slayer Overload, for want of a better term, is going to bring about an opening in our Reality similar to what Glory's spell would have done, but on a monumentally greater scale, as in the Super Apocalypse that Lindsey told him was coming, the FINAL BATTLE referred to in the beginning of the Fray mini-series. Given that kind of information, Angel would have no choice BUT to try to restore the Cosmic Balance. Why didn't he simply tell Buffy what she had done, so that Willow could at least try to correct the problem? Maybe the spell was irreversible, and becoming Twilight, forming a partnership with whatever or whoever the real leader of his current army (imagine Angel/Twilight as the Caleb in this case, with increased powers the same way that Caleb was) is the only possible way to correct the situation. For some reason, Buffy HAS to be kept ignorant of the situation, including his true identity, for some reason that will be revealed at a later date, so Angel has to become Twilight, someone completely unknown to Buffy or any of her friends.
That would explain why Buffy has suddenly become super powerful. The three gods that she had released gave her the additional powers in order to stop Angel from achieving his goal of averting the Super Apocalypse that will release all of their kind and allow them to walk the earth once more, bringing about the end of mankind totally. It would also explain why Giles would (if he actually is) work undercover for Twilight. He is our counterpart of the Wishverse Giles, who destroyed his own universe because the alternative "has to be better."
Given a scenario such as the above, Angel might, almost certainly would, regret what had to be done, but, given what we know of his character, he would nonetheless do what he felt had to be done, even to the point of killing the woman who he loved, one of the few true friends who he had left (Faith), and Buffy's few thousand followers. Certainly, his actual act would be evil, but, just like the nameless Operative in "Serenity," he would be doing everything that he did in order to build a better world, a world free of all aspects of supernatural elements, even himself. Remember what the Operative told Mal? "I am a monster. There will be no place for me in that better world." Like him, Angel fights knowing that, if he wins, he dies, and if he loses, everyone else does.
