My brothers ex girlfriend

I wanna cry for my brother, he did everything for his ex, everything and even though everyone hated her, he saw something in her no one else saw. She was nice at certain occasions, when things went her way. I never liked her but my brother was so in love with her, even after she hurt him repetitively and never ever has he ever hurt her, all he did was give her love. They'd fight a lot, over stupid things. She'd do stupid things, yet he never broke up with her. Until, she cheated on my brother. And he was furious, he broke up with her, and yelled and she was so dry about it. She threw away a one year relationship for another guy, and after that they stopped talking, she cried so bad and apologized that my brother said it was alright and they got back together in 2 weeks. She'd get drunk...a lot... and call my brother stupid and worthless and that's a nobody, and his love for her is stupid, called him so many things, and yet they still stayed. He gave her all the things she pleased. He did what she wanted. I saw it. And 2 days ago she broke up with him. And he cried and she didn't. He tried getting it back, and she didn't want it, he told her she changed, and she said yes. That was his first girl. And for her, that was just another person. I've never seen him cry this much. And it breaks me, because after everything...she threw it away. It was such a toxic relationship but he loved her so much. I remember her always telling me how much she loved my brother, but how could all this be a lie? How could she do this to him? Why was she so evil? He deserved better, but he always thought she was the one.