My life is ****** up?

You didn't actually ask a question, possibly because in your heart of hearts you know that you have created the life you have, and only you can create a better one. You're not going to like this advice, but it's true. Why shouldn't your sister marry? She can still be a good friend. It doesn't matter whether you like her boyfriend, you're not the one that's thinking of marrying him. Making promises to discuss everything isn't the same as actually starting the discussions. Stop blaming everyone for the mess you are making of your privileged life. Take some responsibility for the first time. Decide what you want, and go for it. Dont expect everyone to hand it to you on a plate.