I have a 19 year old son. Are relationship has been strained over the years?

I remarried when he was three. This was in 1994. His father was abusive and a drug addict and not to mention bipolar. I did not know it at the time, he was diagnosed with it 2 yrs ago. My son tells people that he had a rotten childhood because I divorced his father. He has seen his father (who still lives with his own mother at the age of 38) be abusive towards his own mother, so I have always been at a loss as to why he takes his anger out on me. He has always rejected my husband who is probably the nicest person anyone could meet, has been good to me and has tried to be a father figure to my son. My parents and his paternal grandmother pretty much have always given him anything he wants, things that I could not give him. Even though he has not lived with me over the last several years, I have always told him he can stay with us, I have paid all his medical bills, and have always tried to help him when I can. I helped him get into college. His attitude towards me is he will be fine one minute, then go off on me cuss me out. Then this will be followed by horrible text messages. He has treated other family members awful, and has done the same thing to my sister and my brother's son who is his cousin. I have tried to get him counseling, but when the counselor told him that she had a possible diagnoses in mind, he quit seeing her. Blood work was done to check his hormones and thyroid but it all came back normal. I have a feeling that he might have inherited bipolar from his father. But with his constant refusal to get help and meds, I have gotten to a point where I just don't want to be around him. He treats me the way his father did. I was wondering if there was anyone out there who has gone through having an abusive adult child in their life and what the outcome was.