I don't know what you've been doing to rebuild or maintain a relationship with your son. But I can speak as an adult who, as a child, underwent ears of severe parental alienation. The way I would answer your question about (paraphrasing) "What can I do? My son hates me" is this: continue to send cards/letters for holidays, etc., keeping the focus on your son and your hopes for his happiness and well-being - even if they are returned to you. If your son expresses anger towards you, remain calm and speak/write peacefully and, again, keep the focus on him, your love for him, the good things happening in his life, and the good things he has to look forward to in the future. He may be angry at you now, but when he gets older and gains the perspective of an adult, he will (no matter his age) look back at any loving efforts you made to support him and make him feel good about himself. He may want to reconnect with you as an adult (when he's self-supportive and not dependent on others - and when he can even contact you secretly and not have to "defend his betrayal" of anyone who discouraged contact between the 2 of you). At the very least, your continued loving efforts will have a beneficial effect on his self-esteem as an adult. Your efforts will say to him "I was worth it."