I'll try to make the details brief. My Fiance and I got engaged in January of this year. The day after, we visited his parents who seemed very excited and began asking all sorts of questions. Then, we stopped by his brother and SIL house to visit them.The SIL begins talking to me about random things, and assuming she doesn't know about our engagement, I ask her if she's heard. Instead of congratulating us, or even seeming in the least bit excited, she looks at me like i'm stupid and says "we all knew it was coming."A few months later, I decide to ask her to be in the wedding (I don't want to have to pick between my friends so I choose family only). Plus, I figured this would be a great way for us to bond, become friends, etc. When asking her to be in the wedding (she is now pregnant, btw), she looks stunned and says to me "it all depends on how much weight i've lost by then" (meaning after having the baby, who is due eight months before our wedding. She never gave me a direct answer, so I assumed that meant no. The only reason I learn she is planning on being in the wedding is because she told my FMIL that she was in it.So in August my fiance and I had to get our engagement pictures done before we headed back to college (I lived in Michigan for the summer, they live in Indiana) and the only date our photographer could do them is on the day of the SIL's baby shower for her SECOND child (I couldn't get work off that weekend, so I wouldn't have been able to drive three hours to go to the shower anyway). She throws a fit and says some pretty cutting remarks (like all my aunt privelidges are revoked, etc.).So the final straw was when I went to pick up my wedding dress and posted the exciting news online and said "this day couldn't get any better!" to which she has to turn the focus on her and say "no, this day would be better if i had my child."Keep in mind that i have been as supportive as possible throughout her pregnancy. I have offered prayers of support, consistently asked how the pregnancy is going, offered to help in anyway possible. I never bring up the wedding unless someone asks me about it. When I ask if she and another bridesmaid and I can go wedding shopping, she automatically turns the conversation into an "all about her" story and changes the subject. I don't know what to do anymore. Anytime I mention the wedding, she starts talking about herself. She never asks me any information about the wedding. My other bridesmaids are all supportive and very involved, minus her. I'm not looking for her to be at my beck and call, but is it so much to ask that when I ask her to go shopping, or I ask her to be in the wedding, she act like she is excited?I know its too late now to back out. I regret asking her to be in the BP, but I can't ask her to step down. She had her baby this weekend and we have even brought up food for them while they were in the hospital, held the baby so she can rest, etc. But she has been like this since way before the pregnancy, and I'm tired of biting my tongue.What to do?