You know, it's better to be alone than to be wishing you were. I'd rather sit alone in a 1 bedroom flat in peace than listen to his blustering and preaching in a 50 room mansion.
Have you thought of leaving? I mean actually sat down and devised a plan, considered all the aspects & finances? Sought legal advice? Talked to your children, if they're adults and would support you emotionally and assist you in breaking free?
The problem with bloviators like that is that they can wear us down, put us in a state of 'inertia' simply because we're so emotionally drained and tired of hearing their shit.
As far as building a new life or social circle, he probably doesn't want you to do that since you're his 'captive audience'. Another reason to leave so you can go to church (if you're religious), join WI or other clubs, all ways to broaden one's circle and make friends. But do you have any old friends that you no longer really speak to? If so, consider reconnecting with them. All easier to do without him around, of course.
If I were you, I'd be gone. Life is too short and too precious. And we only get one go round on this Earth so we need to do all we can to enjoy it. I'm assuming that, like me, you're of a 'certain age' and possibly DH is retired. That makes it harder to break free, but not impossible.
If you just can't get out for whatever reason, then buy yourself a pair of ear buds and keep them in your ears. When he starts, turn on some music or a podcast. And avoid asking him questions or giving your opinions since that will just start his motormouth.
Frankly, it'd be easier to leave.