My DM had F.F.I and died when I was a child. I have not developed it however there is still a chance. A few in my family have had it and I wake up many nights, terrified that one of my 3 DD's will have it. They are still young and symptoms do not appear until you are older. My DH doesn't seem to have the same fear that I do and I am starting to think that I am crazy, worrying about something that will probably not happen.
I'm very sorry about your DM, it must have been very hard for you. Have you spoken to your GP about this? They may be able to send you to a genetic counsellor who can help you with your anxieties and testing if that's what you decide.