Poor girl. There is no doubt that he broke your heart. At first I thought, hey everybody makes mistake and we all deserve second chance, but then I read he is having this affair for nine months. Its not mistake and not a one time deal sort of thing and he clearly does not loves you. Not from deep inside the heart. It takes years to build the trust and second to flush it down the toilet. You will never be able to trust him and this trust thing, it will hunt you forever. My suggestion, be strong and move on. There are other greater challenges in life than breaking up.