hellokitty,
i symphatise with you...
there are 2 ways you can go about this.
1) if you wanna stand firm, then just tell her that since she has already viewed and measured the clothes herself, and agreed to buy them AFTER she viewed and measured them, then you will not refund back. end of story. but you must be prepared for the backlash lor, ie. perhaps she will pester & hound you for refund, or worse, she highlights her "plight" on the forum and "blacklists" you as a bad seller, and she emails the moderator complaining about you & asking that you be banned fr the forum, etc.
2) if you want the problem to end quickly and without incidence, then just agree to a full refund, but ON YOUR CONDITIONS, ie. she will first have to return to you the items via registered mail (she will have to bear the cost of registered mail, since she is the one who decided to return the items & asked for a refund), then once you receive the items and checked and confirmed that they are all in original conditions, then you will refund the full amount to her bank account. tell her you will not accept the items being sent by normal mail, as you will not bear responsibility if the package gets lost. also tell her you will NOT do anymore meetups, as it is inconvenient for you.