If you don't send the item within your handling time (2 business days for the swimsuit) you will get your on-time shipping metric dinged. The consequences of that mainly apply to higher status sellers, not new ones.
If the buyer doesn't receive the item before the estimated delivery date (which calculation included your handling time) s/he was given at payment ends s/he can file an Item Not Received and get a full refund if it isn't delivered before eBay rules on it, resulting in a defect for you. If you cancel the order (other than upon the request of the buyer, which you should not do as it is NOT the buyer's fault) you get a defect.
My recommendation would be to see if someone else can ship it for you NOW. Or if the buyer is willing to wait up to 30 days before a reasonable time for delivery after you get back. If not, cancel for "out of stock" etc. (do NOT blame the buyer) which is the catchall for any seller-centered reason for cancellation, and take the defect you deserve (and likely a negative feedback from the buyer which you also deserve).
Why did you not take the listing down or otherwise make arrangements for it before you travelled?
