What are the financial obligations for sponsoring a friend

There is no such visa as a K-5 visa. Under the K categories, there are K-1, K-2, K-3, and K-4. K-1 is for fiance(e) of a US citizen. K-2 for the eligible dependents of K-1. K-3 is for spouses of US citizens. K-4 is for the eligible dependents of K-3.

What do you mean by "sponsoring"? There is no legal basis to file an immigration petition based on a "friend" relationship.

What you likely mean is that your husband has been asked to file a Form I-864 (Affidavit of Support) for an intending immigrant. Your husband can review the instructions to the form to find out his obligations under the law. The form and instructions are available for free at www.uscis.gov .

Unless your husband has enough income to sign the form by himself, he likely will be asking you to join in signing the form (via the Form i-864A).

Are you and your husband willing to financially support (generally at at least 125% of the poverty level) the intending immigrant the rest of your life? This is one scenario under the Affidavit of Support.

Your husband and you likely should review your facts and options with your own attorney.