You didnt mention if he was at all receptive to you contacting him. My inexperienced opinion is keep showing up in any way that you can. Send a card or present any time you can. Never miss a holiday. Dont ask him for any thing. Just show up regularly (if not in person, then, mail) Maybe address them to him and his foster family in case there are any feelings of trying to sneak or control the situation. Tell him you love him, and always will, no matter what happens. Make everything unconditional and as guilt free as possible. (For instance, telling him you miss him terribly might add guilt or shame to him.) That you are sorry things have turned out this way and that you want to stay connected with him in any way that he is willing. He knows, obviously, other people also see how abusive she was/is, or he wouldn't be in foster care. He knows she leaves early. Accepting that your mother doesn't actually love you is a horrible thing to have to deal with at any age, but as a child, they often turn it around as "I am not loveable". Seeing you as an ally will force this truth into his head more. It is probably pure survival that keeps him away. Kids know who shows up for them consistently. Do your best to be in contrast to her. I would start a journal or scrapbook or some kind of memento piece for him. Every time you are thinking about him and feel the pain, and dont know what to do, add a memory, a picture or scrap of something that tells the story of your love for him. Keep it with the intention of giving it to him someday, when things have settled down. You absolutely have to believe that things will turn around. Make all your actions about it. Try to leave the fear behind. You are both likely going to be alive for a REALLY long time ahead of you. There are decades of healing, connection, love and family closeness ahead of you both. Think of how much your perspective changed on your mother from when you were his age until now. Things change radically during those teen years. Plan and prepare for when he gets out of foster care. He will need a hand up like all newly 18-year-olds. Focus your pain and loss on getting your life together enough to be there for him, if you are not already. Be his example of how you escape and rebuild a horrible childhood. Life is long and there is so much more hope than you can see right now.