How could someone love there spouse and yet have sex with other men?

Hi, I've always beleived that in a marriage two becomes one in spirit, thoughts, and unity. Which now even what i have always desired from the heart is that my marriage bed be keep pure. Seven years ago while going to a local town about 11am i had a vision if you will of my wife and another man. After gaining my thoughts i then drove back home due to i was sick at my stomach. It was about a two hour drive which landed me home at long about two pm. She was there at the time so when i approach here with what i had experienced she denied it and I could tell by the look in her face she had lied to me. Now just a few weeks ago this burden i have carried all these years she finally told me the turth. When the truth came out it went much further than what i had imagined not only at the time seven years earlier at 11am when i had the vision she told me that was the time she had sex with another man. Then came the worse she went on to tell me she had a one year affair just starting a week after my experience with yet another man. Not all can i write as it would be to long and might bore you. I'm not sure i will be able to shake these thoughts out of my mind for i knew even then she was doing something. My question is how could someone love another yet lay with a stranger and destroy the life of the one who she says she loves so very much..What shall i do now, we are still together. I am completely broken, embrassed beyond imagination, devastated, I need some to help answer this question, for even now i stand and welcome the thoughts of death. I really beleive off all people she would had never done this very thing. She gave the only thing i helt dear my trust a beleif in her away to another man. This i cannot ever regain a pure marriage bond and bed between us.