My Girlfriend Split Up With Me. We Slept With Another Person. Have I Done Something Very Wrong?

We dated my ex for 16 months. We split up without any tips of having straight right straight back together. Two weeks later on I'd a single stand with someone I don’t know. 1 week later, my ex calls and indicates we should try to get back together night. In subsequent talks, she asks me personally if I experienced slept with anybody. Being a man that is honest we reluctantly informed her yes. She actually…