Wow, that's really tough. With dd, we just don't keep anything in the house that we wouldn't want her to eat, but it sounds like that's not entirely possible in your situation. Although if you really don't want her eating Goldfish on a regular basis, just don't buy them. She will get used to them not being available.
Kids will generally want to eat what they see the grown-ups eating, so it will help if at least you are eating healthy. With dd, it has helped to somehow make a new, healthy food fun. We get Pink Lady Apples, and she just loves that they're called that. It also helps just to keep healthy options out and in sight. I usually try to keep something healthy (baby carrots, bell pepper slices, grapes, cherry tomaotes, etc) out on the table. It's more likely to be eaten if it's in sight.