Girl's Behavior

How can people be like this?

Long story short, I had an ex [LDR] with whom I stayed 8 months for. Well the relationship was going very good for the first months.
Then slowly I started recognising a toxicity pattern.
Like DARVO , Gaslighting , Playing the victim, Verbal Abuse..
Well I truly loved her so much.. I did a lot of high level efforts for this person. Made her handmade stuff. And surprising her every way I could. Like one time I wanted to have a pendant of her name on my necklace so I made one using sheet of metal. But I think she took me way too granted.
Whenever I had looked in her profile of facebook just to see what she is upto.. I see she hearts selfies of other guys. Which I found to be very odd. Since she doesn't know any of these guys personally nor from school. I had talk with her about this many times.
Well moving on from that, she had also kept some friends who are male but they were litterally courtshipping her even though she put made it clear to them. I told her to get rid of them since I dont want male friends who liked her and courtshipping her. But she was very hesitant i dont know why.
Moving on, there was a time when I had a fight with one of her friends. It was a man and it was clearly her friend fault. But later when me and her friend fixed up things he sent me a screenshot of my ex saying "He needs to be more mature yk"
Which hurts me that how do you say stuff like that behind my back.
Anyways I still forgived her..
Everytime we fought it was like a war, she would speak bad vurglar languages. Which hurts to hear but I still understood that she had anger issues.
Also, she did used to care for me during my sadness or illness. Being in LDR, she celebrate my bday by buying a cake in her world. She also used to write handwritten letters every monthsary.
Thats what confused me. That does she love me? Or Am I overthinking this?
I found out later in the relationship she emotionally cheated on me. Lied to my face. And any advice to move on from this?
How can people be like this?
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