If my husband cashed in his 401k which was accumulated during our marriage, how does it get handled during equitable distribution?

If there is no agreement Judge makes the decision.

If he cashed out the 401K while you were still married and not separated, it depends on what he did with the money. If he took all the money and is hiding it or bought a house in Jamaica, you still get your share back from him in some form, or you could, as a penalty to him, get 100% of the asset back because of his misuse and abuse. This could also apply if he took all the money out after you separated, as you're supposed to get 1/2 of the 401K. It could be given to you in equivalent value from some other asset, for instance. Call a family law attorney and discuss how this works.

If he cashed it in during the marriage, there's nothing the court can do about it unless he spent it not in furtherance of the marital community (e.g. to gamble). So if all of it was spent during the marriage, with the above kind of exception, there's nothing left to divide.

Generally, a 401(k) is a marital asset. Its distribution is dependent upon all of the facts in the case, the fact that he cashed it in only means you converted from a 401(k) to some other asset. If that was done during the course of the divorce the court will not be pleased and will most certainly make them account for it.

If a marital asset, your spouse would have to make arrangements to pay you half or negotiate some other asset in its place. Have you considered Mediation. Mediation is fast, effective and affordable. Both of you would have to agree to mediate in order for mediation to proceed.