It's natural for the spurned party to want to reach out to you. Infidelity brings out a wildly complicated set of emotions (rage, jealousy, anger, insecurity, fear and doubt). She might want your side of the story to see if her husband is lying or misrepresenting what happened between the two of you. She might want to shift some of the blame off her partner. She might want to make you feel guilty or ashamed. She might want to talk to you out of simple, masochistic curiosity. Who is this other woman? How do I compare to her? She might think corresponding with you will give her a sense of closure. Hell, you might want closure as well. But if that's the case then I urge you to seek it elsewhere. Ultimately, any issues she has should be taken up with her husband, not a stranger.
It sounds like you probably know this, but if you haven't done so already, cut off all contact with him. No texts, emails or phone calls. If you do see him out and about, be polite, but that's it. Be steadfast in your convictions, and you won't repeat your mistake.
I'm not going to harp on you for having a "tryst," as you say, because I don't know the circumstances, and it's far too easy to make blanket statements about cheating that villainize all parties involved. The reality is we all make less-than-stellar relationship choices, no matter how smart or ethical we may be the majority of the time. The clichés are sometimes true. We have to play with fire to understand getting burned. The real test is what we do afterward, how we move on from these choices, and how they alter us for the better.
Anna answers your sex and dating questions every week. Got a dilemma for her? Email firstname.lastname@example.org. Join RedEye Dating for a chance to pick dates, not people.