Your parents are adults. They can pay their own bills. period. You are not responsible for your parents bills, especially not when they are fully capable of supporting themselves.
It sounds like you have some boundary problems. You should read the book, "Boundaries" by Henry Cloud. It's an amazing book, and it really helped me. I'm going to give you some tips that the book would probably explain.
You are being a terrific, if slightly misguided daughter. You think that you owe your parents financial support. You do NOT. Your parents are guilt-tripping you to pay for their misguided behavior. If you still want to live with your parents, explain that you will pay a small amount of rent, if they want you to, but you will not pay nearly half of the house utilities. Come up with an amount of rent you're willing to pay. Grab a trusted friend and have them listen to you explain to your parents that you are not going to buy them any groceries of any kind. No wine, no food. Nothing. If they want something they can buy it for themselves.
If they say that you need to leave the house, then find yourself a nice apartment to move to.
Now before you do this, you need a good social structure. Most likely your parents are going to be annoyed or ticked off when you explain this to them. You need a few trusted friends you can turn to after you give them this talk. I would recommend joining a local church. You can easily find some people there that can help you through this process.
I'd also be glad to help you get through this. DO NOT just keep giving your parents your hard-earned money. Do something about it! Feel free to talk to me more about this.