Writing a letter to the government stating that one is unmarried

I am living abroad, when I came here I wrote in the papers that I am married in Pakistan and wrote my wife's name also. But now as I am living abroad, I also got married here as well. The trouble arises when I need to apply for citizenship for this country. The trouble is this I need to tell them that my previous marriage is no longer valid. In fact I don't want to break my first marriage. Can I write to them that I am no longer in the first marriage, or if I mention my first wife's name but wrong fathers name so that even though I am doing a bad thing lying but I want to save my first marriage. This foreign country just has her name in the records, no picture no other details.