Nope. You are a good person. First, you are reaching out for help when you need it (which is helpful and wise); you are turning to a constructive space to talk with people who understand your struggle (Talking Sober); and you are holding yourself accountable (you are conscious that there are new ways of thinking and behaving that you are learning, and it matters to you).
This is just my experience and reflection, so if it’s helpful I’m glad but if not, no worries: take what’s helpful and leave the rest. 
Resentment is a type of anger, and anger is a necessary and useful human emotion. (Remember the Pixar movie “Inside Out”? The five emotions - Joy, Anger, Fear, Sadness, Disgust - are the same five basic emotions that exist worldwide in all humans. Decades of psychological research on different continents and in different cultures has observed that these five emotions show up in many different ways worldwide (some studies added Surprise as an emotion, but still, just six basic emotions), so the five basic emotions are the basic ingredients of human emotional life. They’re like the three primary colours in art: all colour is a combination of the three primary colours.)
Emotions are the energy that drives life and behaviour on the surface. They’re like the magma and tectonic plates and other stuff happening under the surface of the earth. A lot of the life and energy and warmth and growth that we see on the surface of the earth exists because of that incredibly powerful and vigorous and active crust on the Earth, full of energy and elements and explosions and connections and creation. That’s what emotions are for us: they are the creative energy that drives us.
Reflecting on our emotions, reaching out for support, and using the energy and momentum from our emotions constructively is helpful. In recovery, we learn to work with our emotions in constructive ways (instead of numbing them, which is what we used to do with our addiction).
Anger is a necessary and reasonable emotion. Anger occurs when the way things are (or the way things seem to be) are not the way they should be, and nothing is changing (or nothing seems to be changing). All the anger we feel in life boils down to that, and that is normal and expected and reasonable.
What is happening with your mom is 100% a valid source of anger. Your resentment - your anger - is completely understandable and reasonable and normal. It’s not easy and it’s not fun, but it is normal and reasonable. (I’d be more worried if you didn’t feel anger.)
Resentment is normal in recovery too. I am still processing (and discovering) deep resentments that have existed for 20 years or more. I listen to them in the same way I would listen to a friend who was angry. I listen without judgment; I listen to understand. It helps.
I share my listening with my friends in recovery. I am fortunate to have a short list of people in recovery with whom I have developed friendships, and I will call them or have coffee with them, and ask for input. (Sometimes I just need them to listen. Sometimes that’s all I need: I just need to be heard.) Each case differs, but the listening and the sharing is always helpful.
The next steps depend on the case, but it is always about seeing what I can control, and what I can’t control. (My friends help me see this sometimes.) If I am placing my worth or my value or my choice in the hands of another person, I am not taking responsibility for what I can (and should) control: myself, my choices, and my self-worth. In my personal experience, I often find that my resentments are based in that, or something similar.
Sometimes I write letters and don’t send them, then I store them in an envelope I keep in the drawer by my bedside. Getting the pain and the emotion out on paper - telling my story - helps me to externalize the pain, and it helps me assert my freedom and my independence.
Resentment is good. Not to hold onto forever of course, but what I mean is, resentment is a signal that you have a blockage, a choke point, something interfering with you, and you need to get it out. Think about that. What are some constructive things you can do to help you externalize and process this resentment?
