Whose at fault is it in this argument?

We work at call center so our cubicles are open and right next to each other as well as other coworkers. my coworker/friend and I talked about how she was put on a budget/allowance by her husband. Remember, we talked normally so anybody next to us could hear us. 1-2 hours later she said, "let's have a potluck" and I responded, "r u sure you will enough money as you only have so much money." She got mad at me and later told me she was embarred. I said that if it was going to cause her embarrment why talk about it at work and not in private. She got mad and told a secret that i did not want anybody to know. Whose fault is it and am I responsible at all?