@Hillfarmer, such a good explanation.
Op, please read the post. The reason you are struggling to understand is because abuse is not rational. It is not caused by your behaviour, his stress, circumstances etc.
I had the exact same situation and we had the potential of a good life but Ex was personality disordered (covert narcissist) due to his abusive childhood & genes.
There maybe a pattern to his behaviour, usually the cycle is idolise, devalue & discard. The idolise phase is early days where you are perfect and can do no wrong, often marriage happens in this stage. Once you are commited by marriage or children (or a power inbalance such you are lower wage earner) the devalue starts which sounds like where you are now.
In this phase everything you do is wrong unless you give up your needs completely to serve him. He holds you in contempt which isn't your fault. He will be highly reactive and defensive to any suggestion of your equality and tactics used are silent treatment, gaslighting, blaming you, projecting.
Ultimately you walk on eggshells and the stress can cause you to get physically ill as your adrenal glands will be affected.
The first stage is awareness however it is common to not quite believe what is happening. I spend several years in this cycle but the behaviour got worse. It always does. Outwardly he would be charming and no one believed that he was awful to me. I finally left when I realised he was turning the DC against me. Had I stayed I would have been portrayed as the crazy mum who got upset. I recall asking him a question and he reacted with such contempt that I was shocked. DC came in and asked the same question and he was super charming in his response. I knew then that he had total control of his behaviour and he reserved his contempt for me.
Keep a journal and write down incidents. It is very important to believe you are not being unreasonable and to know that you don't deserve it.
Useful books are by Lundy and Patricia Evans as they explain the power dynamic that operates.
Do you have family? Are you financially reliant on him?