Mine was a little different. My partner was distant for months and I had an inkling it was to do with a girl he worked with. He was going out for drinks after work, texting alot etc... One day he came home real late, drunk and told me that he wanted to leave. Wouldnt give me an answer why so I told him it was because of this woman at work, he admitted it. He told me that they hadn't slept together but that he wanted to be with her. I was totally crushed after 5 years together. We had to stay living together through this and after a month of being 'single' I confronted him, he hadn't been out with her once since he left me. He admitted it was all a mistake and that he loved me. I always said I would never forgive an affair, I know nothing physical went on but it felt worse than that. I forgave him and we have been together nine years now. I suppose ou can't really answer this question without the experience, because you dont know how you will feel. If it ever happened again I would walk away. Once is a mistake, more than that is the end.