There is no single definition of codependency. It looks a little different on everyone. People pleasing, poor boundaries, attracting problems and helping too much are common. Putting the focus back on you and letting go of what the alcoholic does is the start of 12 step recovery.
Resentments are a killer in recovery because they fester and create lots of anger and negative thinking. In 12 step recovery, you learn to list these in a fourth step. But how do you actually let them go? That requires a bit more work - so here are some ways to work it through for good!