Hi Jessica.
It's such a true statement when it is said that our past shapes our present, in some ways. And for those of us with an addiction, it's also true.
But one phrase in your post about your husband stood out for me...
He's used to say to me that he had a hard time opening up his heart because he didn't want to feel that loss.
That may be a natural instinct to do that. But I've learned, since starting recovery early last year, that the last thing I can afford to do is stuff any feelings and emotions, no matter how painful they might be. Things going back to my childhood, or the impending separation with my wife. Doesn't matter.
The sooner owned and processed, these painful things become just that much easier to live with. Otherwise, they remain free standing obstacles to serenity, perhaps the one thing your husband needs the most.
The only thing you are responsible for is your own serenity and happiness. His pain, sadness, discontent, that's all his.
I wish you both well.