You made a promise. In fact you made a PERSONAL Guaranty on the loan. Your assets that would make the loan 'Good' are exposed to risk. Whether or not the business continues to function is not the issue. Your Personal Guaranty is. I'd sit down with a business attorney or an asset protection attorney to sort out your options going forward. Be sure and take the loan paperwork with you.
I agree with attorney Potter. Agreement is agreement and your signature on a promissory note is what makes promissory note enforceable. I would go a little further and suggest considering to honor the note. Courts and people in general prefer to deal business with those who keep their words and anything in writing will stick. I would weight the cost/benefits for avoiding honoring the promissory note with myriad of consequences if you do not. Best of luck.
Disclaimer: This answer is for informational and educational use only. This answer does not create attorney-client relationship. For more details, I recommend a private consultation with an immigration lawyer.