I would never go back to that restaurant and I would have refused to pay. It's totally unexcusable what happened to you and I would have left immediately after the incident. In my opinion that was the only thing I don't agree with, you should have taken your family and left IMMEDIATELY. I would not have left the waiter a tip either. I know it's not his fault but he shoud give his boss hell about losing paying customers.
I mean how is it a patron's fault that a rusty nail gets in their food? That is total negligence and just the fact that they were somewhat indifferent to what happened to you is outrageous. I would have told them and then if they treated me poorly I would have made a BIG scene.
It reminds me of 2 incidents that happened to me, once I bought 2 facturas in a confitería. They wrapped them for me and as I went outside opened the package and I was about to bite into it, I noticed a big green fuzzy spot of mold on the side of it. I thought no big deal I used to eat worms when I was a kid. I was about 10 steps away from the confitería, I go back in, up to the cashier who took the money from me literally 2 minutes before and very quietly told her that there was mold on the factura. She told me, "once you leave the shop you can't make any claims". I said, I was just here a few seconds ago, she looked at me with an attitude crossed her arms and said, please move away from the counter. So me, the big mouth New Yorker, BLASTED her with words and started yelling about the moldy rotten food in the place everybody was looking and some people walked out. I took the facturas I bought threw them behind the counter and took a cardboard tray and loaded it with cookies that were on the counter and walked out saying "call the police, rotten food sellers" of course they didn't dare say anything or even follow me out.
About 10 years ago I was in Paris at a small restaurant on Boulevard de la Motte Picquet. It was a very informal place for a quick bite. So I order a salad and a sandwich, they bring it out quickly and the next thing I knew I am on the floor seeing stars. The chair collapsed under me. At the time I weighed about 170 pounds (180 now), so it's not like I am a fat dude or anything like that. They came over to me and said "why are you on the floor" and I said "Do you think I want to be?" "They said, "oh you broke our chair" and didn't even try to help me up! So here I went of on them yelling and screaming and getting my backpack off the floor to leave. They blocked the door and said I had to pay for the chair and my food, which I ate about 3 bites of. Of course I screamed yelled bloody murder and I charged past them and out the door. As I was on the sidewalk yelling back at them they slammed the door. The next day I had a huge black and blue mark on the right side of my tushie. I hate being abused by businesses, thank goodness it hasn't happened to me often, but when it does out come the claws. Paying customers deserve to get treated with respect, if something goes wrong the business is obligated to solve it and take the hit if it's their fault. The customer should not be made into a victim. There are plenty of idiot customers, when I had my shop and that happened I would just ignore them or throw them out. But customers who had a valid complaint or a problem with my merchandise would get complete consideration, exchange or refund at THEIR discretion and an profound apology. It should be no other way.