My Ex Husband S Alcoholism Killed Him Last Year. Id

Question: my ex husband's alcoholism killed him last year. id been our son's closest parent, tried to co-parent with fairness and our son's best interest . but after the death, i moved in so our son could remain that year and graduate with his friends . Slowly, I began to observe he was rejecting me fully, shutting down, yet using same critical condescension , patent ingratitude, and provocation of his father. Parental alienation is difficult to spot, because it's insidious . My son is lost to me now; he has new twins, and is a very young but loving father. Its hard to absorb the cruelty with which he rejected me, stating "he has his own family now." He won't call or write, returns none of my calls ,and claimed I threw he and his girls out on the street, when it was he who lashed out at me and after 19 years as his pal/mom/champion, he won't even give me his address, or a place to send thing to the girls. i have a broken heart, but after 15 years being maligned by one alcoholic narcissist, I wont let myself be ignored, maligned, or disrespected by his son. Sadly, he was my only family and my XXXXXXX Did the alienating of me and subsequent total rejection of me instill over my ex's endless need to tear our son to pieces? I was told that with families in this alienating parental dynamic, addiction is common. what can i do to to stop placing myself in no-win family relationships with alcoholics or abusers? ? Lastly, if i simply let my son's cruelty to avail itself I will despair, not hyperbole . My grandkids were 6 months when he took them away, and this was a year ago. I love them and miss them, and although I was always right to his side when he's asked me, without hesitation . Please explain long term prognoses for the alienating and the alienating?