Selling a vehicle with upside down loan

My wife and I currently have a Ford Explorer that we owe just under $15k on. My aunt passed away and left me her Jeep Grand Cherokee. We also just had another child so my wife is not working. In order to save some money monthly I wanted to get rid of the explorer. Unfortunately the value of it is about $12k. (Carmax offer). Would it be wise to sell it and write a check for the difference now, or should we keep the explorer for another 6 months or so and pay it down and hopefully not lose value even more over that period? We’d obviously be paying about $70/mo on insurance just to let it sit. I do have some money in savings but I’m just trying to soften to blow on the whole scenario. Any opinions?