Hi there ~
I understand your concerns. I believe you and you fiancee are ready to go to rehabilitation
for psychiatric dependence on IV substances. I believe that you are at serious risk of loss of live as well as medical problems that could be fatal. Irrespective of what happens to the welling in the arm, if NA is not helping I strongly recommend that you get yourself and your fiancee help with dialing 1800273TALK so as to get the resources in your local area to find help with dealing with the situation. Please consider the serious and urgent.
I hope this helps. Take care of yourself and have a lovely day!