Why can't some people see how much they hurt someone?

So, my ex has hurt me in so many ways, and says she sees no wrong in her actions.
She's dated one of my colleagues casually when she dated me because she wanted to 'have fun'.
She broke up with me because of religious differences and got mad when I didn't want to stay friends after I took her and her family out the night before.
She kept asking my family how I was doing, and stalking my Facebook.
She took out her frustrations on me from the ending of the relationship and how I made her feel she didn't matter over a year after the breakup.
Reached out saying God told her to, and asking us to get back together.
Kept talking to me about the former colleague now stalking and harassing her because of her mixed signals in the past, knowing it was a sore spot
Said how the other guy she dated was a better kisser and knew her better than I would.
Went on a mission and asked me to date others
Rejected my marriage proposal because of the mission
Broke up with me on Valentine's day because of the mission
Refused to reply to me during and after the mission
Following me to work just to walk by me
Stalking my social media still.
Why can't some people see how much they hurt someone?
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