How could i be so blind?

My wife had a affair that lasted at least 10 months with co worker I finally caught on when I got the phone bill and saw a number being called many many times so I called the number and a lady answered I asked her if she knew a Tracy she said no then I asked her if her husbands name was Jim. She said yes I had heard her say that she worked with with a jim then she went on to tell me she was pregnant and that they had planned it. Wow was I shocked