I think this is absolutely beautiful, especially in this color for spring/summer. And, clearly, it sparked something in you to cause you to buy it so impulsively. I would take a day or two to play dress up with it. Style it with a few outfits from your closet to see how it works for you and whether that joy is still there, somewhere. If you don't rediscover the love that made you buy it and it doesn't bring you joy, only shame and regret, you shouldn't keep it because you won't use it. And, worse, you'll feel bad every time you see it in your closet.
I wonder why you would sell it at a loss on Vestiaire, though, when surely you're within the window to return it?