Urgent: How should I continue to store this Merlot wine?

Store it in the refrigerator. That will be far better than where you have it now. It would be great if you had an inert gas to lay upon it. I brew beer and have a tank of CO2 and that would be better than nothing. The idea is to keep the ravaging effects of oxidation off the wine. The well stoppered bottle stored in the dark cool refer will do for now. Try to drink it soon, very soon.