So sorry to hear of this Danky.
My son viewed one of those four villas when we were looking to purchase. He said it would have been his first choice had it been big enough for us. He loved the style and the setting. We drove past only the other day.
If the developers are building within regulations then I feel there's little you can do. The property we bought here in Ovacik, which had just a few farm houses nearby when we viewed it just over 2 years ago, is slowly becoming enveloped in new builds. We still have amazing views and the Babadag side of the house is supposed to be 'orman arazi' and not be built on but we aint holding our breath.
It's gutting but doesn't necessarily mean your property is de-valued. Sule Beder, our avukat, is brilliant but not sure what she could do if the builds are above board.
Might be worth contacting her though,
http://www.sulebeder.av.tr/