Question on remorse felt by cheaters

[cetane97]

Hello everyone...
I'm a 21 yr old student from India. Sometime ago I got interested in learning about how extra-marital affairs happen and how they affect everyone concerned (morbid curiosity???) …. I researched on this subject by contacting a few betrayed spouses (BS) through e-mail and by reading what the wayward spouses (WS) and the BS posted on a number of infidelity related forums.
I had been trying to find out what the former WS feel in their stage of remorse during recovery. For a very long time I had been thinking that the remorse that the FWS feel is because of their guilt that they have hurt their spouses and the thought that their marriage has been desecrated. A few months back I read that the introspective journey of the FWS is more painful than the hurt felt by the BS. That falsified my previous beliefs about the FWS’ remorse… I asked myself “If I were the WS will the agony that I feel for having hurt a person be as painful, let alone be more painful than the agony being felt by the person I have hurt” I believe not.
So there must be other reasons for the FWS feeling a deluge of emotions like shame, guilt, desolation, self-loathing, fear and so on… None of the reasons I could come up with proved to be strong enough to cause that amount of pain that many FWS say they have felt.
Does anyone have an idea about what are the thoughts that make the WS feel this way?
I have my own theories. But before talking about it I needed to know the opinion of people who know more about this. Could you guys help me?

P.S: I’m an amateur and do not know much about psychology… the only book I’ve ever read about human behavior is “Manwatching” . So could you please be as descriptive as possible with ur replies?