How do I react to my mother-in-law showing extreme favoritism towards my sister-in-law.?

Question

A few months after me and my now husband started dating his brother started dating my soon to be sister-in-law. Ever since then it has been total competition on her part and my mother-in-law just fuels the behavior by showing extreme favoritism. A week before we got engaged they got engaged...purposely. We chose our date in May and luckily they chose theirs in September, so I thought. For our wedding my mother-in-law made it so difficult by complaining about everything. She didn't make anything easy. She even put a picture of my husband and one of his exes on the table as part of the center pieces for the rehearsal dinner. It was a joke...a bad one. Anyway, now my brother-in-law is getting married in less than a month. This woman has bent over backwards to help them out. All she talks about is their wedding and how to make it the "best". I am distraught!!! I have only ever been nice. I do not like confrontation and have been sweeping it under the rug so to speak for two years. I am at my breaking point and feel like at any moment I am going to tell them what I really think.

Answer 1

my advice- stay aware from her/  i stay away from my mother in law, she is a real *****.  you are not going to change her feeling/

Answer 2

Don't let her know any of your plans and keep your distance from her. As for that picture joke she pulled, I would of went ballistic on her ***.