How do I get over the fact that my boyfriend left me for a girl who's a bully?

I was dating my ex-boyfriend for a year. I had a group of friends at the time, and one of my close "friends" used to bully me in that group. She used to make fun of my intelligence in front of people, and then one night she drunk-admitted she was insecure about her appearance and envious of me. She also used to tell me that attractive guys would only want to sleep with me and not commit because I'm not worth it. She was a bully, basically, due to her own insecurities.

Well this girl had always gone after people I was interested in to compete with me. But after only one year of dating, I didn't know at the time but she started texting my boyfriend behind my back. I guess he was flirting too despite knowing she was a bully towards me and then cheated on me and left me for her. After that, they both began putting me down. And out of jealousy I guess, she would try to insult me in front of him to create more chaos. When I would stand up for myself, she would tell me to shut up and that I'm too sensitive.

How do I deal with this? This happened a couple months ago but I still feel awful about myself. It's as if I'm so bad that a bully is better than me?

How do I get over the fact that my boyfriend left me for a girl who's a bully?
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