How do I collect a debt from somebody whom I loaned money to if they haven't made a payment and have said recently that they will never pay me back?

You need to file a claim against your boyfriend's dad in circuit court. You may have a claim breach of contract (as well as potential other claims depending on the facts of your case) for his failure to pay back the promissory note. Obviously, the specific facts of your case will control what, if any, claims can be filed. If you are successful and you get a judgment, then you can move toward collecting on that amount.  If you file the action (or get a judgment) and he files bankruptcy, then you would need to file a claim in his bankruptcy case called an Adversary Proceeding. In the AP you would have to prove a claim like fraud (or another claim allowed under the bankruptcy code) in order to prevent the debt from being discharged (e.g. forgiven). AP's are difficult though. Just because you have a claim does not mean you will have a successful AP. When you start litigating in bankruptcy court it is imperative that you have competent counsel.  Given that you are out over $60,000.00 (assuming interest is also owed), it is probably worth you seeking legal counsel to help you start the process.