My husband had a cyber affair.its over 4 him,hes sorry & wants 2 work things out w/me.How do i let it go?

I can see he is trying, I cant stop obsessing over where i was when this was going on. Our marriage is worth the effort. ive taken the phone calls logged from his bill and placed them in conjunction on a calendar along with all of our ims, phone calls, & events. I am in disbelief that this happened right in front of me. I most definitely wasnt neglectful to us. I think it helps. I want to let it go now but this nagging feeling that if i do let it go, i am sending a message that it was alright.