Difficult situation. Unfortunately, delays in financing are all too common. Here are some things you may be able to do. If you still want to close the loan on the new terms, then I would proceed. If you don't like the terms, then you should have a financing contingency in your real estate contract which will let you get out without a penalty. The penalty or $5,000 should be only if you decide not to proceed. With respect to the landlord if you need more time, try to revoke the notice and move out later. In the future, never give notice until you have the keys to a new place. I would not advise suing Wells Fargo, suing for $5,000 is hardly worth it. Plus, what about a different lender. Also try negotiating a return of your deposit. Talk to your realtor.
Please note that this answer is not legal advice, and should not be relied upon. Each state has different state laws and procedures. A review of all documents and a consultation at a minimum is necessary to render effective legal advice. This answer does not create an attorney client relationship. Consult an attorney before you decide on a course of action.