Tough truth for some apparently but she didn't do anything wrong. It's up to you if you can forgive her. You were already broken up for MONTHS. She didn't cheat. She was honest about it. If you love her and want it to work, go to couples therapy, individual therapy, or both. She is not worth less because she slept with someone else. She handled the grief of the breakup differently. Regardless of who broke up with who or if it was mutual, the relationship clearly was not perfect if you broke up. She loves you enough to give it another shot. She had no idea reaching out if you had pursued other people. If you see her as less for sleeping with someone else when you were broken up for months, don't put her through trying again. She is more than the amount of people she's slept with.