Not using a language for some time seriously affects your capability of communicating in that language. German for example, there was a time where I was able to hold up a conversation (even if a simple one) in German, now I can hardly understand anything apart maybe for "Nein" and a line I will never forget: "Bist du klein oder bist du gross", written on a poster I don't remember what was for, on the wall of my first level school.
These three years in Sweden have caused some changes in my linguistic skills. Plainly enough my vocabulary in my mother tongue is not as good as it used to be, and Swedish has started competing against English as my second language. The latter one I would have no problems with if my Swedish was simply overtaking my English, but the fact is that I feel I'm loosing my English to make space for Swedish. Do I possibly only have space for two and a half language in my head?

What happens if I manage to become fluent in Russian then?

Well, I guess that's one mystery waiting to be solved (eyes gliding to the Russian course book on my shelf)..