I'd recommend couples counseling too, and also counseling for her by herself. Something emotional led her to those affairs, and that same thing might be driving her to not want to have sex with you, no matter how much she wants to reconcile. A therapist would help her figure it all out.
I would recommend couples counseling. For many women sex is so much more than it is for men. If she is stressed, upset about something, feeling guilty, this could cause her to not want to have sex.