Comparison is a thief of joy

Last four months are the hardest. I constantly comparing myself with other girl. She's younger, prettier and better than me. Had fight with my boyfriend for almost everyday. It get pretty routine that every two days we will have this argument. To be honest, I feel like I suffered with bipolar or split personality. I am seriously tired having fight with him. Endless argument, endless drama, endless yelling, screaming. But on the other side, she is happy with her boyfriend, giggle, laughing out loud. While me and him, we constantly yell to each other.