Mona, I replied on your profile page, but I'll reply here too...
If you remove folks from your friends list, they still stay in your Mafia, but you can't help them and they can't help you on jobs....
You lose a bunch of potential EXP!
Better idea is to break out your friends list into smaller lists so that you can keep up with them separately.
I have a number of different lists that I can switch back and forth to.
I have a list for real world friends, one for MW and one for KrAzY folks....
If you need help, let me know and I can walk you through it.