Husband and wife. Wife co-signed. Husband refuses to make timely payments.
In co-signing, you become a co-obligor, in that you joined in the obligation to the loan company, bank, etc.
You likely had a solidary obligation, in that the obligee/the one who is owned the obligation can come after either you or the other individual for the full amount.
BTW, are these two still married and in a community property regime? To some extent, you could argue both signed up for an obligation, regardless if one is not paying, since you have community funds.
Here's some information for you about these obligations. The obligor that is penalized for the failure of the other to pay could have an action against the other, eventually.
You could also talk to the person who made the loan. But honestly, the point of co-signing and things like this is specifically so that the loaner can be paid if one of the signers cannot pay.
solidary obligation = each obligor/ee owes (or is owed) the entire performance; can arise by agreement or by operation of law, but it is never presumed!
renunciation of solidarity = obligee may expressly renounce in favor of one obligor; effect is that that obligor is only liable for his virile share (but the renounced obligor still bears the risk of insolvency of another obligor)
remission of solidary obligor = released from the obligation and is no longer bound; risk of insolvency of another obligor is no longer with the remitted obligor, but rather with the obligee.
solidary obligors have actions for contribution or indemnification among each other for having to pay more than their virile share (or anything if solidarily bound as a surety).
The answer given here should be considered general in nature and should not be considered legal advice, or that there has been an attorney-client relationship established. It is always suggested to retain the counsel of a lawyer for legal advice specific to your situation.