At this point she'll either become your sister in law eventually, or they'll break it off and it could be awkward for you two. Everyone tends to get kind of dreamy and focused in a relationship at the beginning, and friends feel left out. It's normal, it's part of them bonding, and you shouldn't be too jealous. If you're polite and patient, she'll likely still be your friend after she gets over the infatuation and needs her social support network again. (Given the tone of this post, that's a long shot for OP.) If you want to maintain the friendship after she and your brother break up, or especially if you want to enjoy a positive relationship if she ends up as your sister and law, give her a bit of space, stay friendly, and don't take it personally.

You should be happy for your brother, dating a horny ***** is every man's dream!

She treats you like shit for ten years? And you haven't moved on to better friends? Really?

Her being a shitty person isn’t reason for you to ****-shame her, my dude.