Yes, you got to let them go. I got 3 houses in las vegas, and they all went all the way down in the water. I stop paying for all of them for over 6-8 months while i am still staying at one and collecting rent from the other two. Well, what i am geting now is only a fraction of the down payment (25%-30%) I put down 4 years ago, but at least you are getting something out of it and stop the bleading.
my only inspration that supports me is: even a smart and wealthy person like Donald Trump had filed bankrupcy before.
sometime, you got to do what is best for you, and I think let go of the house is the best option for you at this time.
dont forget you you can stay in the house without payment for about 6 month to 1 years depens on how busy your morgage handling the foreclore in your area, and think how much $$$$ you can save for thoese months.