Am I wrong for feeling that way? not knowing what they did while at his house. I just don’t feel like our relationship will ever be the same again?

So me and my ex had broken up but we got back together. He end up telling me how he had met a girl they would text all day and night. They went on two dates , he went to a cookout with her , he met her daughter , he took her fishing , she had been in his house. We are trying to make things work between us now but nothing feels right to me anymore
Am I wrong for feeling that way? not knowing what they did while at his house. I just don’t feel like our relationship will ever be the same again?
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