If Russia will "collapse" economically (so far it hasn't, not really) it won't be just because their relations with Europe broke down, but because a united front that includes Europe, but also the US, Canada, Australia, and most of their allies has all decided to impose sanctions.

Russia's economy is mainly export to Europe (>50%). Asia comes second. The Americas only account for about 6%.

Of course sanctions on export to Russia will also be felt, but not as much as losing the money of Europe.

Yes but much of Russia’s exports are commodities, which are traded on a global market. If Russia loses Europe, they can find other buyers. They may have to adjust the price, but they will still be able to sell to somebody.

It’s different from China which is exporting far more finished goods. If America stops buying high end electronics from Chinese factories and starts buying from Vietnamese factories, then those exports just vanish from China’s economy. There is no backup America to buy the goods to keep the factories running.

The logic of the sanctions is that in the long term they prevent Russia from profitably exporting by denying them any imports to improve their productivity.

In simpler terms, how can you just switch to a different market when the pump to make the gaz is unavailable to you.