Credit should be avoided as much as possible I think; it's too easy to get out of control unless as a person has strong self-discipline.
It's a shame you're in the situation with the bank due to someone else's failure to show ownership and responsibility. I hope you manage to clear the debt and move on. You'll be a little wiser too I think. Also, I like your motto, it's a good one to remember.
RE: Interest irresponsibility