her actions led to X becoming Abnormal
Wasn't it the Script, considering it's implied that it's Ayin telling X to fade away without a trace?
Anyway, regarding the vote:
1a: If it's OOC, the option wouldn't be offered, we've already seen an example of that previously
1b: It being a IC choice does not necessarily mean that we will like the consequences OOC
1c: However, no matter how it goes, we will have a Distortion shaped problem to bury the immediate reactions (that of telling, or of the thought process leading not to say anything) under once we go back
1d: Owing to this, do we want to speak (and deal with the impact of Angela's reaction) or not (and deal with the possible awkwardness and the potential second-guessing in the future)? The next opportunity is in an indeterminate time in the future, after all
2: On one hand, we've told the girls, who we consider to be our family, why not Angela too?
On the other, a not-insignificant part of that decision was because they objectively needed to know, even if they can't fully understand; that does not apply to Angela.
(However, in the long term this WILL have to come out eventually anyway, can't have a Patron Librarian without settling the full details of this I imagine)
3: It's fairly likely Angela will understand if we tell her or if we say we don't want to talk about it either way, but deflecting will have costs (not that anyone is voting for that).
However. Trust has to start from somewhere, does it not? Might we use this as the springboard?
I personally think that if we tell her the spaghetti quota in the next update is going to be entirely filled by X

, so we won't need to worry about Angela putting her foot in her mouth there (as mentioned, it's likely she already knows, but the fine details like X being incomplete and being able to draw out EGO does have implications as to what to do next on Angela's side).