His take on what he wants from our relationship is ‘I ask you for nothing and you ask me for nothing’.
Is that what you want from a relationship? From a husband? From the father of your children?
Replacing words in your thoughts isn't really going to help. All it does is pretend you're not angry. Calling him an arsehole at leasts admits you're angry, that this is not behaviour that you want. It stops you minimising and denying your own feelings. You are entitled to feel angry with him, his behaviour is cold and hurtful.
He doesn’t want to hear how his behaviour makes me feel and doesn’t want to discuss how he feels. I don’t think that is ever going to change.
Well, that's a good insight.
What is this?
Self-absorption is a very good word for it.
Are people normally able to not be interested in their partners feelings?
Sounds abnormal but that doesn't help because even if he does have a diagnosable condition such as a developmental delay, PDA etc then he isn't likely to own it or to take action to help you live with it. You'll still be on your own with it.
How do I live with it?
Do you want to live with it? I mean, if you had the choice?
it scared me that after years of having sex with him he either couldn’t tell if I was into it or me not being into it had no impact on his enjoyment.
Neither of those are good. But you recognise that it's not good, which is a start.
The therapist could give you some coping strategies but there's nothing that will really protect you from the long term effects of living with someone who doesn't respond appropriately to your feelings (or anyone else's by the sound of things)
there are various schools of psychology that promote the idea that you can only work on yourself and it’s unhealthy to rely on others (for example gestalt psychology). I’m not sure I buy it but plenty of people do.
Absolutely. You work on yourself by understanding that you can't change someone else and that you don't have to continue to like them or love them or live with them. But you may need to do a lot of work on yourself before you reach the stage where you can accept that. Where you can accept that your own needs are valid and you don't have to stay with someone who will never meet them. Whether he loves and respects you or not (which is rather questionable) sometimes love is not enough, you also need a partner who can act in a loving way, someone who can be close to you.
I just wish I could work out where he’s coming from, understand his behaviour and file it away.
It is often less painful to focus on "why is he like that" than "how does him being like that make me feel". 