From 2005 to 2007, I owned a few nail salons and ran my business by myself (sole proprietor). In 2008, my (former) friend said he wanted to buy into my business. He offered me $50K to buy in, and I agreed. From there we ran the business as a partnership, but we didn't have an agreement in writing. Business wasn't very profitable, but we split everything. In 2010 he kind of abruptly walked away from the business (moved away, and we didn't talk at all after that). Just last week he called and said he wanted his $50K back, or he would sue me. Can he do this? Do I have to pay it all back?Follow up: isn't there any chance that a court would say I sold half my business to him for $50K when I let him become a partner? And if so, didn't that money become mine? When he abandoned the partnership, the business really wasn't worth that much, so if I have to give him half what the business was worth, that might be ok.