What should I do to keep my marriage?

I married a woman I completely adore. Unfortunately I had to move overseas to study. Not having money to get my wife the necessary air tickets to come join me I got involved with another lady who helped me with money to get my wife to join me. Unfortunately at this point I am so into a relationship with this second lady, technically having her as a mistress. This mistress has continued helping me and my wife financially and materially. Given this complex relationship I am having serious war of words with my wife. My challenge is that getting this mistress out of our lives will basically put my wife and me in a serious financial crisis given all the medical and other bills and since my college stipend can't cover my bills. The option would be to loan more money and send my wife back home but this will make things tougher as she will never trust me not to continue my relationship with the mistress. What should I do? Being poor already had us live apart with my wife for six years of the last eight years we have been married!