Scared I'm being deceived by my wife

I am 30 year boy I had married last year. at our first night my wife told me about her past. she said it has gone before 4 years. but I always scared that does she deceiving to me or does she lying. I asked her she said that she loves me lots she cant live without me. but I always think that if she is telling lie. she takes oath of our unborn child even she is ready to polygraph test. please suggest me what should I do. please please please help me