Two things:
This issue is parallel to the perennial GYE question of, "Well, how do I know I am an addict? Maybe I am just a ba'al tayva and have a bigger than normal YH for schmutz. Yes, it bothers me, and yes, I know all about 'doing teshuvah (I've done it seventy-five times already, :o on this very same thing!). But who says I need to bring out the big guns; that I must actually learn how to live a different way? That's kind of drastic, you know. Maybe I'm just a nice Jewish boy with a little problem?!"
And for me, the response is:
Well, you may be right. The only question is whether it bothers you enough. True, a normal person might see the cost of what I am doing and freak out, saying, "are you a lunatic!? You have everything going for you and look at what suffering you are causing yourself and those around you...what about your future - can't you see that it will not stop tomorrow, just like it didn't stop today? (and you were pretty sure yesterday that it would...) Before this is over, it will certainly will destroy everything you have and a lot that others around you have! You absolutely need to stop!"
Nope. They are wrong. Until I see that I need to stop, I cannot stop. And even then, I absolutely cannot stop on my own. That seems to be the way it works. Unless I finally come to view myself as having a hopeless - yes, hopeless - problem, a problem even bigger than I am, I will not get the help I really need. I will stick band-aides all over myself...haven't we all?
So it is with working the 4th step process on our emotional mishegaas'n. We can't seem to really take it as seriously as we must, until we are bothered by it; until we see that it really makes our lives unmanageable; that it is something we really do not want any more. That is the 6th step.
You can write it out, as you have, but the question you are now apparently asking is, "How do I know if I am tired of this resentment yet? That I do not really need/want it any more?" It seems to me that you are on the sixth step, chaver.
That's the first thing.
The second thing is this:
Is this a big fish for you? OK, fine, I am not suggesting to sweep it under the rug, but could you perhaps have greater resentments and bigger, wider-ranging issues. Issues that feed your addiction? You - we all - probably do.
Let's ask Hashem to reveal a bit more of the truth about ourselves so we get the biggest bang for our buck. There may be elephants in the room. By all means, pursue this lead with all you've got - but be ready for having some scales removed from your eyes and take Hashem's lead for further growth.
Hatzlocha,
Dov