So, 2 votes for walk away because she's been a serial cheater for most of your marriage, 1 vote for letting this go because she's giving you transparency and that's how you found out about this.
IMHO, your situation has better odds than Curtis'. He never went dark, he didn't wait for his ex-wife to recommit to the marriage, and he never required transparency like sharing her passwords.
I encourage the general DB tenant to SLOW DOWN on making emotional decisions--e.g., on staying or going, and on full transparency vs. full disclosure. It's normal to be hurting, it's normal to need time to process.
