Something similar happened to me with my Dad. A few years after I graduated from college and moved away, he took "early retirement". A few years later, we discovered that he had spent everything, and run up tens of thousands in debts. Some of that debt was on a credit card that I had closed, but had left the paperwork in my old room at home. He always intended to pay the money back before I found out about it, but he just kept spending. In my Dad's case, it was partly gambling and partly spending like he still had a high paying job.

My first piece of advice would be to protect yourself financially. It may sound cold to say this, but you could end up in a very scary place financially, and you have to protect your financial future. Check your credit report and make sure there are no surprises. Keep your credit cards, bank cards and social security numbers protected. In the long term, you want your Dad to get help, but in the short term, you need to make sure you don't get sucked in as well.

Secondly, realize that you can love your parent and support him emotionally, but still keep a firm line when it comes to finances. "Helping" is never as simple as it seems, and getting your finances intertwined with your parents will just lead to frustration and resentment on both sides. I had to learn that I couldn't control what my Dad did, and while I could be loving and supportive when it came to encouraging him to get help, it was not a good idea for me to try to tell him how to budget or offer financial advice. It put me in the situation of being the bad guy and affected my relationship (without really helping my Dad). I was better off being the supportive daughter and having him go to someone more objective to get financial and/or psychological help. If I wanted to help financially, I presented it as a gift and always gave it as something like a grocery store gift card or paying a bill, not as cash. Since your Mom may be impacted by this, you may want to help her, but I would suggest staying away from giving cash that Dad could spend.

And finally, don't feel guilty about your parents paying for your education. If they hadn't paid for it, they probably would still be in the same financial situation. If he's spent everything, he would have spent that too. Your parents wanted that for you, and they're probably grateful to have been able to pay for it before this happened.