Guessing thats his mother. In my opinion I dont want her to come back into his life. Its okay to not forgive and this should be one of those cases. Just cause someone is ready to apologize it doesn't mean that you're obligated to accept and forgive them, no matter who they're. Whats she did was terrible simple as that. Can he let go of his hate and accept it? Sure, and honestly he should do that, and not let himself be tied down from his past. And his new family will allow him to do that. He doesn't have to accept his mother into his life because what he once missed out on, he now has just with different people.