How tho?

How do bad people live with themselves? How can someone go and actually cheat on a person they claim to love and pretend to be happy and just go on living their life? Like how do they even sleep at night? I couldn't imagine cheating on someone I loved, I wouldn't be able to live with myself let alone sleep at night or look that person in the eye again. It honestly breaks my heart that people give their heart to someone only to have that person take it and crush it between their hands so easily. If I found someone who loved me I could never even look at another person because I'd treasure their love and their heart as if it were my own. I'm sorry this isn't intended at anyone specific I'm just having a hard time and a bit of a rant