First of all, yes I can imagine the situation you describe, as I have experienced it myself, and so have many others on this board. Many can understand and empathize with your pain. Kudos to you ( and all) who found the strength and courage to leave such a difficult situation and make a new life.
However, "bitterness" and "anger" is a response that we have some control over. It is an understandable response, but we do have a choice whether to let it go as quickly as possible and move on and have a happy productive life. Some people hang on to anger and bitterness and nurse it, nourishing it and feeding it, helping it to grow bigger and stronger until it becomes the dominant "mode of being" and interacting with others in the world. It is the person who is bitter and angry who continues to suffer long after the original offense is over.
Other people may then tend to avoid them because it is pleasant to be in the company of someone who is always angry and bitter.