@Aete: I've spent quite some time with PoE so far and from what I played I can honestly say that it has the potential to be the best game ever in the genre-- the economy system is brilliant, the way they handle skills is amazing and allows for incredibly unique builds, the crafting/item enhancement stuff allows for so much customisation and of course, the passive skill tree is just bonkers (but in a good way!). Can't wait to dive in :)
Pardon my French, but your friend sounds like a big ass douche. Still, and for the sake of friendship (although I personally wouldn't want anything to do with a guy like that-- but hey, that's me), talk to him first. But my advice would be to always tell the truth.
The pause button is your friend, never forget that-- you can issue commands while the game is paused, so that helps a lot. Also, try to upgrade your doors early on and then just watch those pesky invaders run out of oxygen and die as you open the airlocks behind them ;)