Basically mate this is what happened to me and what I assume has happened to you...
All this time you were together, you have been feeding her ego and building her self esteem. She treats you like sh1t and you still forgive her and still love her. That's a lot of power going to her head. She feels like she can get away with anything and feels like "the prize".
She feels very confident right now and so she can go and see if the grass really is greener and go play the field.
Meanwhile, she has had the opposite effect on you. She's damaged your confidence, trodden you into the ground and left you feeling insecure and uncertain of yourself. Your ego has become dependent on her and you need her validation in order to feel whole.
The worst part is, your low confidence shows in your bodylanguage and behaviour, so you start to find that other women are less attracted to you. Meanwhile, she is oozing confidence and feeling good, so she appears attractive and finds it easier to socialise and meet other guys.
This is why most people seem to get more attention when they're in relationships. They give off this confident and secure vibe that makes them very appealing.
It sucks, it really does! It's a great injustice, but life just isn't fair. This is why so many people stay in abusive relationships and forgive cheating and so on. They become dependent on their partner for validation and to make them feel worthy.
This is another reason why no contact is so helpful. It stops you from feeding her ego even more and it stops her from wounding your ego, and allows you time to heal and regain some confidence. Whereas if you keep contacting her, begging or trying to insult or hurt her, you're just feeding her ego even more and making her more confident to meet other men, while you're decreasing your confidence, self worth and losing your dignity.
If you bounce back from this break up quickly and started seeing someone else, she'd start to question herself "How did he get over me so quickly?", "Did I not mean that much to him?" or "Am I really as special as I thought I was?" It knocks her off the pedestal and wounds her ego.
After my date with the underwear model after the ex from the previous post broke up with me, my friend said he saw a physical change come over me. The last time he saw me (only 2 days before), I was walking with slumped shoulders, my face looked drawn and I looked like a man with no value, but he said I was walking taller, head up, spreading out more when I sat down and I was giving off more positive vibes.
What's more, my ex had lost her biggest source of attention and ego inflation (me) and she started spiralling down. Nothing was going her way.
This is why when I broke up with my recent ex, I expressed the break up was a good thing for both of us and long overdue and I wished her the best finding a new man. It was just my way of evening up the power dynamic - letting her know that all the flattery and ego stimulation is gone and she's on her own now, with no safety net to fall back on.
I have no idea how it has affected her, but in my mind, it just helps me to keep my head high and walk away with dignity.