i do think you need to talk to dh more.
the issue isn’t the principle - he wants to divide the sssets he came into the marriage with between you and his own children. Fair enough
but, if part of those assets including your home, that you have contributed mortgage on, care, maintenance bills etc, and have lived in whilst value has increased, his kids are benefitting from your contribution too , but to your detriment.
personally, I’d be asking him to value house and assets at point he entered marriage and ring fence that with the 50:50 split, then asset gains from point of marriage go to you first on his death.
if he won’t do that, I’d be asking to sell now, buy two homes , rent one in your name, to give you security
right now yes, you stand a good chance of having to sell your home to release equity he is leaving to his kids, and that’s not a static sum, the more the house value increases over next 20 years, the more his children will be owed and you’ll still need to sell
has he said what he expects you to do for housing in event of his death?