West Virginia is fairly accommodating if you're looking for a legal way to separate from your spouse.
A separation agreement is an enforceable contract between you and your spouse.
Ideally, it should cover all bases, including how you're dividing up property and debts, who will have custody of your children, when the non-custodial parent will have time with the children, who's going to pay child support and how much it will be.
It should also include any provisions you want to make for spousal support.
If you eventually decide to divorce, a West Virginia judge can incorporate the terms of your agreement into a divorce decree, assuming it covers all the bases and isn't grossly unfair to either you or your spouse.
Otherwise, you'll have to go back to the bargaining table or have a judge decide outstanding issues at trial if you eventually want a divorce.