What do I tell other SAs in my class post reneging?

Reneged from my SA offer a little while ago.  As of right now no one in my old SA class knows.  However, some of the off cycle SAs who accepted the offer are now starting to reach out again, as I was supposed to begin soon.  I reneged for personal reasons and would like to maintain my friendships with these people, but obviously my career comes first.  What do I respond to the "hey how are you doing" texts if at all?  Thank you for your help!