Holly

My soon to be sister-in-law is getting married. In fact, she got engaged when she found out that we were "talking" about getting engaged. She dated the guy for 2 weeks and all of a sudden was engaged. We kind of stopped our plans because she has become bridezilla and I don't want to ruin my time planning with family and friends because she is being mean. (I know I should go ahead with our plans but if you knew her you would understand). Anyway we are all going on vacation in a few weeks and its on my birthday weekend. I was excited to hang out with my future in laws and boyfriend. My boyfriend's sister is making a day and a half trip on our 4 day vacation because she thinks she will miss us talking about her. She also decided to invite her future in laws on the day of my birthday so they can hang out with her parents. Its like we can't have a weekend where we don't talk about the wedding. How can I be strong and not let it spoil my time?
I'm trying to not let it bother me but it does. I can't say anything to her mom and or her because they both get WAY TOO defensive. I have looked forward to this trip for 4 months.
Thanks guys! Its sad because the sister is actually one of my close friends. She is older than us and always said she should be married before us. She is very competitive and it seems like all she does is compete now. I am actually not assuming these actions but know.