Aloha Karen,

Welcome to the forums!  I am also over 50 and just starting on the violin, but like you, have also been exposed to the piano.  In my case, I took five years of structured lessons, then went on my own, until I joined the Navy.  After three decades off the piano, I finally got one and began playing again.  I also have loved the sound of the violin/fiddle and purchased one about a month ago.  It is quite different from the piano  But as someone else here pointed out, you'll be able to read sheet music already, which is a plus.

I have found that the two instruments can be complimentary.  On the violin, you use your left hand to stop the strings which requires finger power.  As I've been playing both violin and piano, I've noticed that playing the violin has actually helped to strengthen my fingers such that playing the piano has been made a bit easier.

Good luck in your violin playing path - it's more difficult than it looks, but if you take your time and master the "little" things, such as the violin hold, the bow hold, and especially bowing motion (something I have yet to master), everything else will just fall into place.  Don't be shy to ask for help.  I have been treated with the utmost respect here, even if some of my questions seem to be rather elementary.  Also check out the rest of Fiddlerman.com - there is literally tons of information here, as well as very knowledgable people.