ENRTE EMJ MADE INCORRECT TURN TOWARD CONFLICTING TFC.

Narrative

WE WERE OVER VILLS INTXN ENRTE TO JFK AND WE WERE GIVEN DIRECT TO JFK. I PUT IN THE DTO COMMAND FOR DIRECT JFK. THE PLANE STARTED THE TURN TO JFK; AND I CONTINUED WITH NORMAL COCKPIT DUTIES. PASSING THROUGH A 110 DEG HDG (APPROX 50 DEGS AWAY FROM THE DIRECT COURSE TO JFK); THE FO SAID THAT 'WE ARE STILL TURNING.' I TOOK THE PLANE OFF AUTOPLT AND STARTED AN IMMEDIATE TURN BACK TOWARDS THE N. ABOUT THAT SAME TIME; ATC CALLED ABOUT OUR HDG. CTR GAVE US A 360 DEG HDG; AND AFTER WE WERE RE-ESTABLISHED ON TRACK; THEY RECLRED US TO DIRECT JFK. AFTER I ARRIVED AT BOS; I TALKED WITH ATC AND THERE WAS PARALLEL TFC THAT WE TURNED TOWARDS. THEY HAD REVIEWED THE TAPES AND DETERMINED THAT THE CRITERIA FOR A TFC INCURSION HAD NOT BEEN MET; SO NO FURTHER ACTION WAS GOING TO BE TAKEN BY THEM. NO FOUL; NO HARM; BUT I DID EXPLAIN WHAT I THINK HAPPENED. ON THE FMS; THE DTO JFK WAS #9. AFTER THINKING AND TALKING ABOUT WHAT HAPPENED; I THINK I MAY HAVE HIT THE #6 DTO; WHICH WAS TO A POINT BEHIND US; AND I DIDN'T CATCH IT WHEN I DID IT. OUR SIDE SHADES WERE UP AND THE HORIZON WAS NOT CLR. THE VIEW OUTSIDE THE COCKPIT WAS BRIGHT AND WHITE. I'M NOT POSITIVE ABOUT THIS EXPLANATION; BUT IT WOULD EXPLAIN WHAT HAPPENED. IF THIS IS WHAT HAPPENED; THEN THE MISTAKE WAS MINE.