Contract law is your friend. You claim that he breached an agreement (even if it was not signed). if indeed you are correct, there are pretty much 2 remedies: 1

Contract law is your friend. You claim that he breached an agreement (even if it was not signed). if indeed you are correct, there are pretty much 2 remedies: 1. make him fulfill his obligations (either by speaking to him or getting an attorney) 2. demand to renegotiate the agreement, or even breach it yourself. for example, he should have less equity because he did not invest enough. explaining this legal situation to him will probably make actually going to an attorney unnecessary