How do I handle my sister getting engaged 3 weeks before my wedding?

I realize this problem makes me sound like a jerk, but I am kinda upset. My sister got engaged last night and I am getting married in three weeks. It was a complete surprise, but her fiance was well aware of my wedding seeing that my sister is my MOH. It really hurt me, because now a lot of things that were going to be about celebrating my wedding are now about her engagement. I feel like it was really inconsiderate for him to do right now, he could have waited three weeks, but I feel terrible for being mad about it. Afterall, it’s a wonderful thing for my sister…but I feel like it “stole my thunder” a bit. What do you guys think? I am really struggling with how I should feel, I feel selfish for being upset, but I do think it’s a little justified. Help!