For me the problematic dynamic came from having things upset me and build up until I would get so angry it would explode outward. I grew up learning to hold it in, so I had no idea I could talk about problems with people. It wasn't so much letting go of the anger as talking about feelings and difficulties with people allowed me to avoid hitting that breaking point and over time, the anger and resentment has faded. Additionally, those conversations led to a level of trust where I feel like I can reach out to the person when something comes up or even strongly supported by them.
Coming from alcoholic parents, you might want to check out Al Anon. I found that and Codependents Anonymous invaluable as places where I was surrounded by people struggling with many of the same social issues I did. Also, it was unique in that it's an environment where talking about these sort of things is encouraged and invited, in public I tend to find that people find these topics uncomfortable and unwelcome.