If a couple in a marriage separate and one gets on Medicaid, food stamps and child support services, is this considered a legal separation?

Under the laws of all states in this country a legal separation is deemed when a couple separates with no intent at the time to reconcile. Usually a filing of a petition for a legal separation at the county court house is in and of itself evidence of the legal separation as a matter of law between a couple.

The facts of your matter do not indicate a legal separation unless the parties do not intend to reconcile.

In Idaho a legal separation is generally one where a proceeding is filed and there is a determination - at least temporarily - as to child custody, the amount of support for you /spouse and kids, division of property and payments of debt.  THis does not sound like that situation. Good luck.