Do you think I overreacted and I shouldn't have quit?

NO, i think that you shouldnt of left your Clmate join in in the first place even though you say that he does everything awesome and stuff it seems that he only wanted credit for himself...I dont want to make a big deal out of it but i suggest you go back and RUIN the project. You worked too hard and take everything back and start a new one for yourself make them work hard at what you did and then just advise them that "Hard Work Should go a Long way and that nothing should be taken for granted." Now Let me ask you something I do understand the thing that you were saying like oh he just joined, well i think that after he joined that it went all down hill from there.