how to make Partnership Deed with friend in startup

Hi ... we are two partners in business (50:50), both have invested 8 lacs. To execute business operations smoothly, I invested 4L more of my personal money - saying that it is from a friend (and thus a loan which we need to return). After some months of operation, the other partner wants to exit and found a buyer who can buy his stake. Now as part of deal, I am asking that the 4L loan from 'friend' be settled - to which the incoming partner agreed and shared 2L (50%) of his share. The problem is that i am just gettting 50% of my money back (since as partner i am expected to 'return' 50%).