A licensed real estate agent who sells multimillion-dollar estates on Nantucket repeatedly told police and witnesses the Westfield couple he is accused of striking while driving drunk appeared "out of nowhere" on Route 28 in West Yarmouth on Saturday night, according to court records made public yesterday. Westfield firefighter Kevin J. Regan, who was killed, and his fiance, Lynda M. Cavanaugh, who was badly injured, were lifetime members of the private Sons of Erin Cape Cod club on Route 28, where drunken driving suspect Paul G. Dennehy, 55, of South Yarmouth told police he and his wife, Cathy, had last been prior to heading home before the fatal crash on the same road.