Yes, they sound highly toxic and emotionally abusive. My DP comes from a similar type of home, as do I. I've been in therapy for the past few years but its not something he's interested in.
I try to make our home a safe place where things are orderly and reliable. We both like things clean and tidy so we have similar housework standards which helps. If I'm going to be late home, I always text him to let him know, as he starts becoming very anxious if I'm running late and he doesn't know why. When we argue, we stay respectful and as calm as possible - no raised voices and absoutely no name calling, slamming doors or anything like that. I often go silent when I'm angry or ovewhelmed, and DP says this makes his highly anxious, as he wonders if he's caused me to feel that way. So I try to work on telling him how I'm feeling, even if I don't want to talk about it in great detail at that moment.
I would suggest listening if/when he wants to talk about them. Avoid making any suggestions but do lots of validating of what he says - 'that sounds really painful', 'that must have been really hard', 'you must have felt very lonely', that sort of thing. Support his decision to go for minimal contact. Let him know every time you're proud of him, or you think he made a good decision, or did something kind.
Ultimately, any healing that happens (and he will have a huge amount of healing to do after surviving a family like that) has to come from within him, but having you very firmly on his side will help hugely.
One last thing - the feelings that you are left with as an adult having grown up in a toxic family can be terrifying. He may not be ready to face what he feels, let alone share it with you. He may well have very strong feelings of worthlessness, emptiness, loneliness, huge sadness, anger, rage, and a very strong sense of injustice. And that may all be topped off with a huge dollop of guilt because he feels he 'shouldn't' have any of those feelings in the first place!
You sound like a lovely, caring partner