I'm am not a psychologist, therapist or anything of that nature. I am, however, a Codie.
You feel bad because basically you have trained yourself to feel bad. People like us think the bad is our fault, the good could have been good if we didn't... Well, maybe you don't feel that way but I sure do in addition to feeling bad when I try to put an end to friendships such as the one you are speaking of.
This is where you get to use all that work you have been doing and put it into action. Stand firm!! Be strong!! You are right. Yes your reaction is normal for how you 'USED TO BE". Just tell yourself that you don't feel that way anymore, you are now strong.
Be well,