As your Auntie I want to tell you to trust your gut instinct and practice some safety measures for yourself and your kid while shopping.
Are you fat? Well, I guess it depends on who you ask doesn't it? You've already been judge and jury so it doesn't appear that any other opinion matters. You know this is not only destructive to yourself but keeps a wall up against others.
We need to remember how resilient and smart little kids are. They adapt much quicker and easier than adults. Talk to them about their fears. Are they mimicking you or do they have genuine concerns?