How do you keep from being cynical after being betrayed by someone you loved with all your heart?

Mine was a decades-long marriage. I trusted my husband and never suspected that he was having an affair. He was remarried within 6 months. I have gone through various stages since my divorce over two years ago. But I find myself starting to feel cynical. How do I stop that? What worked for you? I feel that I am years away from wanting to start a new relationship.