As far as the title of this thread, "I don't want to have a stone heart..." I have a different take on that.
I am much more loving when I let the addict/alcoholic make their choices and reap the benefits or suffer the consequences on their own than I was (am) when I control and manipulate their lives. When I am operating from my co-dependent/enabling place, I have selfish motives, or motives derived from ego or fear.
I love/hate the 12-steps. lol