Resentment is poison. The longer you are doing something (or in a relationship, etc.) that you resent, the more poison you take in for your soul. The sooner you can get out of that situation the better. We might think that the "angst" and "anger" is good for our writing. I disagree. I find my writing so much better when I am content and fulfilled. I don't need to be angry to write about anger. I don't need to be despaired to write about despair. In fact, the happier I am, the better I am as a writer because I free myself from all that unnecessary emotional baggage. I can focus on creating. Then again, I write about love. I assume if you write horror, it might be different.