Not guilty by reason of insanity. She will be held until she is no longer insane (which could be never).
We live in a society where we have decided that although doing the crime, we find certain people to not have the requisite mental state needed to be punished for the crime. This exists for situations where it would be unjust to punish someone for commiting a crime. Should she probably go to jail for ever? I think so, but thats just me. However, we don't have a l"ets just do whatever we think is just" legal system. That kind of legal system gets a bit scary sometimes, hence the "insanity" defense. For the record, her thinking that "Satan was inside her and that killing the youngsters would save them from hell" seems pretty damn insane to me.
It sucks, but the "insanity" defense exists for a reason. William Blackstone said "Better that ten guilty persons escape than that one innocent suffer."