Before finding the girl of your dreams, you need to reach some sort of closure in your first relationship. If you don't it will always be looming over your mind and you won't be able to concentrate on anything in life at all, let alone finding your true love. So the right thing to do is to be honest with your wife and talk to her about your relationship. I am sure if she does not love you anymore she will understand you perfectly and both of you could be on your separate pathways in life again.
In the eyes of the law, if you are still married there is no possible way of making your other relationship legal. You need to let go of the first relationship and start anew with no guilt no pressure and a clear mind to enjoy and make the most of your new life.