I bought a house worth 500 grands and know its only worth 200 grands after 6 years what can I do?

I bought a 500 thousand dollar house about 6 to 7 years ago and know the value of the house is 200 thousand dollars. I am very sick about this knowing that I will be paying over double the price for this house. Is there any legal action I could take or any loop holes for benefits or aids of any kind? Also if you were me what would you do? I dont want to mess up my credit but at the same time I dont want to be a slave to this over priced house which I feel is illegally taking advantage over a hardworking middle class person. By the way I live in California.. All answers will be appreciated. Thanks