Setting aside your hurt for a minute:
In practical terms, there is really little point in you making a will. If you die intestate (without a will) in the UK, there are rules about who would inherit. First dibs goes to the spouse, they get the first £322,000. Since you say "Truth is , I have nothing to my name" that would mean everything of your nothing would go to him anyway.
Rules here - https://www.gov.uk/inherits-someone-dies-without-will
Did he mean life insurance, rather than a will? It is always sensible for both parents to have life insurance. For a working parent, it can replace the lost income, for a non-working parent it can pay for childcare etc. to replace their non-financial contributions.
Now - you were hurt by his comment, and from your comments it sounds as if your marriage is not a happy place to be. You say he does not contribute financially - does he contribute to the family otherwise? Three under-10s is a lot of childcare. Does he run the domestic side of the household? Because there's a big difference between an engaged SAHD and a husband who spends all his waking hours on his XBox.
"I'm tired of having the world on my shoulders."
A family should be a team, what part of the load does he carry? Earning, housework, mental load - what does he contribute?
"if I confront him I know he'll gaslight me or make me feel silly ."
Has he done this to you before?
What do you think would make life work for you? Him sharing the load? Or him not being there?