Jehovah will provide for sure. Through some sort mental power (as he did with King David when he lift the census) Jehovah will control your mind and tell you to support your parents. You may think that you are doing a good deed but no credit goes to you. It's all Jehovah.
You have to bring some reality to your parents. It's your duty since you are the mature person in the family and likely the most affected by their irresponsible behavior.