According to the ATF database, there are 5 registered FFLs in Middletown, Delaware.
303 WHITE PINE DRIVEMIDDLETOWN, DE, 19709
4783 SUMMIT BRIDGE RDMIDDLETOWN, DE, 19709
1224 CHOPTANK ROADMIDDLETOWN, DE, 19709
864 OLD SCHOOLHOUSE RDMIDDLETOWN, DE, 19709
503 MAIDEN CTMIDDLETOWN, DE, 19709