I'm always in favor of giving a second chance - but I'd definitely bring your husband. I, too, think it 's a good idea to ask him to wait for a few minutes before coming in and see how you're treating initially. Bet your bottom dollar the clerk will be nice as soon as hubby arrives.
Also - as the store owner, I think she needs to know it's hurting her business to have a rude person there, son or not.