Who should pay for the wedding when the couple has been living together for 2 years?

Our daughter is 31 years old an just got engaged. The couple has lived together for 2 years. While I am very happy for her I have mixed feelings as to who should pay for the wedding. She has posted her engagement on Facebook with the beautiful ring on her finger. She is looking to have a traditionally focused wedding with all the bells and whistles. She is very excited about the wedding, which she should be. She and her boyfriend came over the other day and her boyfriend asked us for our permission to marry our daughter, and we said yes. Two days later she and her boyfriend came over to go over her wedding plans. She wanted to know how much money we can contribute towards the wedding. I told her we can give her some money towards the wedding cost. She then said she thinks we should pay for the whole wedding. I sat back in my chair and my head started to whirl with dollar signs and my heart started to race. I then said, " Honey I know you would like to have a wonderful wedding, something like a big traditional one. Your father and I been married for 33 years and had a beautiful wedding with a few guest on a gorgeous day in June outside. If your looking for a traditional wedding, that went out the window when you both started to living together. I'm willing to give you some money. She started to cry and got up and ran out the door sobbing loudly. Her boyfriend followed her outside and then they both left. We love our daughter very much and have a good relationship but we have to stand our ground. I don't want a wall between us. HELP!