a terrible thing to have happen! in my opinion, if you have the heart to start over, I think you have to mentally prepare yourself to only have what you can guard. that's the way of life I think. if it were me, I would cultivate the reputation of being a dog killer of any dogs that came on my place. people learn to keep their dogs up if they want to keep them.
you either have to accept that other people will be careless of their animals and thus rob you of your right to have livestock safely on your own place - OR, other people learn that you will do what you have to do in order to protect your place and your livestock from predation. it's kind of an 'either/or' situation in my mind.
sorry for your troubles