My brother treats his fiancee better than he does to me. What can I do?

I love my brother. We used to spend so much time together. When the family first met his girlfriend she was so nice. Since they got engaged everything has changed. I was excited to be a bridesmaid but because my brother chose someone else instead of one of her brothers to be his best man, she said that i couldn't be the bridesmaid. I was upset when i heard that. She gives out to my brother when we see her, she doesn't talk to me anymore. One time i was sick when we were all to go out for dinner and she said to my brother that i always get migraines when we all go out for dinner. I wasn't happy about that. One time her and my brother had a fight and he came back to the house. I tried cheering him up but when we were watching a film he was texting her constantly. I feel brother spends more time with her than me. I miss all the fun we had. What can i do?

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My brother stays in her house 4 days a week. I barely see him. He buys her a lot of stuff fir her bithday, valentines day and Christmas.
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Last year i had an accident and she didn't even ask how i was or was i ok. My other brothers gitlfriend asked how i was and what happened when she heard about my accident. We see and hear from her more than the fiancee.
My brother treats his fiancee better than he does to me. What can I do?
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