Sameer Sharma shrugged off the concerns of his superstitious mother when, to celebrate his fifth wedding anniversary, he booked a Mediterranean cruise that began on Friday the 13th. The inauspicious departure time was the only one available, said Sharma, 30, of Stoneham. Just hours into their time on board the Costa Concordia, Sharma and his wife, Divya, 26, found themselves hanging over the edge of the ship in a too-full lifeboat that crew members struggled to lower to the water below, the massive ship leaning over them as it slipped farther into the sea. The Sharmas are one of four Massachusetts families coping with the aftermath of a harrowing experience aboard the luxury cruise ship that ran aground then tipped over off the coast of western Italy Friday.