I signed a motorcycle away under duress

I owned a nice Harley Davidson that my TV personality boyfriend pressured me into signing over to our next door neighbor in FL while I was in NH so that it could be registered in FL without me there. My boyfriend was trying not to have a lot registered in his name due to liability with the TV show, etc. I didn't want to do it, but I was also running a business for him which provided some of my income and he threatened to take that away plus make my life miserable, and put extreme pressure on me. He also was renting a home I owned with my mother (now deceased) in NH and could easily have refused to pay rent, etc., after tearing it apart for renovations and never fixing it, so I didn't know what to do. He had me in a terrible financial bind at the time. Therefore, I did what he asked even though I didn't want to. We left it that way for a year because I was rarely in FL, but then my boyfriend died suddenly and now the guy refuses to give back my bike which he never paid a cent for.