Just tell them the real reason of your leaving kindly.. i'm sure they'll understand whatever reason you stated. And hopefully one day when you decided to visit them again, they'll kindly welcome you back..
Well i'm glad that i left my old clan in a good way, that few days ago when I decided to visit them for the first time, they still remembered me and even warmly welcomed me back after 11 months long since the departing. Promised them to pay another visit to spend my birthday with them soon..
Anw, good luck OP!

