'then no-one can keep you in a country you don't wish to stay in!'
No, they can't. But they can keep you from returning to that country to live with the child.
You need to see a solicitor in person.
I can see where he is coming from (disregarding situations in which the husband/partner has or is abusive, violent or addicted to substances and refuses to get help).
I'm from America, my husband is Scottish and our children were born here (I now have British nationality, however).
If we were to split up, well, I'd be on my own here, too. And he'd never consent to my taking our children out of the country permanently.
And tbh, I don't blame him one bit! If the shoe were on the other foot, nor would I!
I chose to have children in an international relationship.
There are consequences to that.
And one of those is that if we split up, I have to make my life here whilst my children are young as really, it's in their best interests that they're in the same country as their dad and he has as much contact as possible.
Not in my best interests, perhaps, but that's life when you have kids.