Forgive or let go

I recently realized that my wife is cheating on me with someone at work. I have noticed for a long time that she behaves strangely. She stopped cooking at home in the evenings, began to disappear more often, stopped hugging me. I tried to talk to her - it gave nothing. I started asking our mutual acquaintances, and they just kept repeating that if we have problems, then I should think about getting a divorce in Utah. I think they know something too. I just don't understand what to do, fight for her, for the truth or leave her