You clearly fear him, OP, whether or not you consciously realise this. I recollect putting this possibility in front of my mother - I grievously feared my violent and probably dangerous alcoholic father - and she had to think about this and process it for some time before acknowledging that this was the case. Boiling frog syndrome is real. They charm you at first. Then they crank up the heat so gradually you don't realise you're being scalded, and the 'frog' who stays in situ for the duration ends up being boiled alive.
I know that the 'scales falling from the eyes' moment is a very, very painful moment of recognition. Sometimes it's less a moment than a very gradual awakening. But that realistion is also the key to your freedom.
Your son has evidently recognised the fear in you, or he wouldn't have made the suggestion of moving without telling your husband where you are. As a daughter who was once in a similar situation, I know that sometimes children can see this before their parents do, and sometimes we can even open their eyes to the unpleasant fact.
I think your son has given you some very wise advise which, in your shoes, I'd be inclined to follow.
Wishing you all the best, OP. It's hard, but some of the things worth having in life often are. And nothing is impossible.