Relationship. Together we can mend e?

I did something really wrong and unforgivable. I am in a relationship with someone since four years... We both love each other a lot. We wanted to spend our entire life together. But a few months back I kissed some other guy twice. And since I was feeling bad about it, I confessed about it to my man. Now he is really upset with me. He doesn't want to trust me. He loves me, he's broken, but I know together we can mend each other's broken heart. But he just doesn't want to have a relationship anymore. I don't want to be without him I really love him and I know, he loves me too. I want to be with him forever, marry him, have kids with him, grow old together. He always used to say that our time will come because we never really gave each other much time because we were concentrating on our careers so that we have a better future together. But we had spent time together. We love each other and I can't live without him. I've gone vulnerable. We two can help each other. Together we can mend e