Sounds like you don't just have memory troubles, but factual troubles as well.
Russia is indeed a major player in BRICS, but the Chinese economy is fully 4 times as large. Even Brazil's GDP is greater.
Now, how a dust up in the Ukraine will sink an economic union that the rest of outweighs Russia by 6 to 1 in GDP is beyond me. The Brazillians, Chinese, and Indians are not being heavily impacted by this.
Start learning some history. This is about the fact on the ground that it's extremely difficult to defend Western Russia without having at least a neutral Ukraine. It's just not far enough from Europe to Moscow. The military in Russia has a long memory, and it includes Napoleon and Nazi Germany invading. The Russian high command knows that the defense in depth and the long cold winter retreat in both cases was what let them win. Without the Ukraine they get very nervous.
This conspiracy theory that it's all to undermine BRICS at the behest of the Rothschilds or some other bogeyman/illuminati is laughable.