Dear Calypso:
You have resentment toward his parents because they hurt him. He is hurt as a result of them mistreating him in the ways they did. He is angry at them too, this is why he told you the stories that he did. He has been angry at them (and jealous of his sister) for a long, long time.
I suggest that you do not express to your boyfriend that his parents did their best and any such thought, that you don’t encourage your boyfriend in any way to get together with his parents, or his sister, that you don’t encourage him to reach out to them, to keep trying to get their love.
I suggest you let him know that you are on his side, in his corner, that you let him know that you heard him, that you feel empathy for him, that you love him.
Unfortunately, a girlfriend cannot easily make up for a lack of love in a man’s early home, the love he didn’t get from his parents. Not easily, but with time, being gentle with him, patient, never fighting (being assertive but not aggressive with him), providing him a different kind of home (once you live with him) “will “give him what he is missing”
Do make sure you are content in the relationship, that it works not only for him, but for you too.
anita