I think you need to explain a bit more to us. Who owns the house etc? Ages of kids etc to get more practical advice.
You don't need his consent to see a solicitor or start the divorce ball rolling. What you have describing definitely is unreasonable behavior.
You've made your choice now just get on with it. Stop feeling guilty it's not a useful emotion.
I paste a variation of this fairly regularly:
Information is empowering.
If possible find some friends/contacts that divorced well. Ask them for lawyer recommendations.
Get appointments with recommended lawyers. 2 reasons for this. It's important to find a lawyer you can work with. I got lucky with no 4.
While waiting for appointments get all your and his financial information together:
Tax returns
Bank accounts
Salary slips
Savings accounts
Investments
Life insurance
Pensions
Mortgages
Debts
Assets
Get the house valued
This will enable a lawyer to tell you what you might reasonably receive.
Divorce for unreasonable behavior as cited in your op.
50:50 childcare is normal but sounds unlikely. There are sites like entitledto that will tell you what you might be entitled to from the state. There are also maintenance calculators.
Write 2 lists in terms of kids, house, cars, maintenance etc:
What you'd like (copy to lawyer)
What you'd accept (private)
Normally I'd say Don't tell him what you are doing, but perhaps you should.