Your husband is lying to you. You can be on the mortgage, it doesn't matter that you're on a low income. For a mortgage, the bank will look at your combined income, so his and your salary together.
Surely you can Google what deeds are, or how mortgages work?
If this story is real, then your husband is definitely, definitely abusive. Abuse isn't necessarily about shouting, insults or hitting, it can be more underhand, like what your husband is doing.
In a normal, non abusive marriage you should be equals and you should feel able to discuss finances, property and jobs without feeling like you're treading on eggshells, which is what you're doing. No one should be crossing sexual boundaries, ever.
Just look at the facts:
-a 40 year old man senior in his job went for someone much more junior and only in her 20s. Why is that, why would he not go for someone of his own age and status who is an equal?
-he's refusing to share finances, put you on the mortgage/deeds and give you access to money, even when you were raising his children. He shows annoyance and gets cagey when you want to discuss finances.
-he's now trying to manipulate you into giving up your job by making childcare difficult for you - getting angry when you ask him about his shifts, refusing to compromise. It shouldn't be only you working around his shifts, you should be working around each other.
-you say he pulls down your pants around the house and has had sex with you in your sleep?? Wtf, this is rape and it's bullshit that he "didn't know". Even if it's true that he didn't know, it's still rape. He treats your body like property. It doesn't matter if it's not happening anymore because you don't sleep in the same room, the fact it's already happened shows you what sort of person he is.
I'm sorry, I know you don't want to believe that he's a bad person, and he may well have some good qualities - abusive people aren't always all bad. That doesn't mean they aren't abusive. It's why leaving an abusive relationship is so hard.
Whatever you do, don't give up your job. You'll be even more vulnerable and dependent if you don't have an income of your own, however small.
Get yourself clued up on finances, websites like Money Saving Expert and Nerd Wallet are good starting points.
And speak to Women's Aid, they'll have good advice on abuse.