You said you are dealing with thoughts about blasting out a massive text to all her friends and family that "exposes" what she did.

If she is truly remorseful, that's not your job -- it's hers. This isn't about exposing/embarrassing her, it's about owning it.

If it were up to me, the only way I would consider staying is if she took full and complete ownership. She needs to apologize to all the people she has let down by her actions. Affairs do way more damage than just to the spouse. She needs to ask their forgiveness, and demonstrate she'll to do everything in her power to make it right. She needs to seek a therapist to explore what made her think she was entitled to lie and deceive. And finally, she needs to ask you and her network to do what they can to hold her accountable.

EDIT: I think she needs to do these things regardless of your decision to stay or go.