What do I do?

2 very trusted friends just told me that my fiance, who I'm marrying in 10 days, has been talking to another girl. At first I was skeptical, but they started feeding me lines from his texts to her and they're identical to what he used to tell me word for word... I love him so much, don't know what to do but cheating is the unforgivable for me. I almost don't believe it. I honestly don't believe it but I know that I should.