When you discover your partner has been cheating, it's always a huge blow to your self-esteem. Most people are very hurt and angry, but also feel very diminished by the experience. They can take a long time to get over the experience and it can damage them for future relationships.
Some people hide their anger, yet continue seething.
Sometimes they wonder if it wouldn't even up the situation if they had an affair themselves. Six months ago, my husband suddenly confessed he'd had an affair with a woman he met while he was out of the country on a business trip. He said he wanted to tell me since he felt guilty and wanted to make our marriage work. In the heat of the moment I lied and told him I'd also had an affair with a younger man. He said that since we'd both cheated, we were even and we could both make a fresh, loving start with each other.