My fiance cheated on his ex wife. How can I be secure with him?

They had problems. She was jealous. She was overweight and wanted him to accept her no matter what. He has a masters degree. He is very well educated but he worries me with his past. I have a hard time talking to him because he is a perfectionist. I feel the only way to see if he will cheat on me is to set up an fake email in the name of a woman and send it to him to see if he will reply to her. But part of me is scared to see the results and part of me feels as if I am setting my self up for heartache. So what should I do?