It is important to be objective about your own career and not be emotional about your friendship with them. If they are good at heart, they will understand you eventually. If not, you are wasting your time anyway. You want to be loyal to folks, but this is a situation where you have to be loyal to yourself as well.
This is part of the learning curve we all go through and it seems you have learnt some important lessons already. I have a lot of senior friends that I didn't get along so well with professionally (because of our different styles of working) but on the personal level we still meet for lunch although we don't even work at the same company any longer.
It's ok... if I were you I'd go find another job and then just tell these guys that an excellent opportunity has come by. Perhaps give them a 4 week notice instead of the regular 2 weeks so they can find someone. I don't think you owe them much more than that.
I used Windows for over 10 years and moved to a Mac in 2009. There is no way I am going back anytime soon. Amazingly, I only realized the problems with Windows after using the Mac for a while and then switching back to Windows for a day to fix an urgent issue. The usability issues lit up like lights on a christmas tree.
Here is what happened. I tried to install a tool on Windows, which required an updated version of the .NET Framework. So instead of doing what I wanted to do, I started doing what that little app wanted me to do. When I tried installing the .NET framework, it wanted an updated version of the MSI (Microsoft Installer). So now, instead of doing what the app wanted to do, I started doing what the .NET installer wanted me to do. You get my drift?
In the 2 years I have been using my Mac, I have not once come across words like virus, anti-virus, drivers or seen any avoidable alert boxes pop up. I am no Apple fanboi. Really, OSX is my preferred OS simply because it does not get in the way and let's me do what I want to do.