Pelosi's not screwed even if she was briefed, if she continues her push to investigate, because a public official who allows those crimes to be committed, and then works to try to correct their mistake, comes out better in the long run than one who allows them (or who plans them and carries them out) and then tries to cover them up. Pelosi will look even more heroic if she potentially faces concequences herself but presses on anyway. The rest of them will look like cowards and slimeballs (which is what they will be).