Bro.! Please stop seeking to reconcile with him. You shall never find peace and satisfaction with this man based upon the game that is being played by him.
From what you wrote, you did him a favor and he didn't want to reciprocate professionally. He didn't want to contribute his fare share to assure that he could continue working with you. That reeks of obligation violation.
Furthermore, payment in cash means he doesn't want to have his income tracked. The fact that he will work for "cash only" tells me that he is involved in an unethical and potentially illegal game financially and wants to usurp whatever rules that govern his financial situation.
You are doing things legally, morally and ethically and he expects you to not do this to have him involved. He does not have the right to complain if you offered him an opportunity to work with you under specific conditions that prevent YOU from getting in trouble.
Brother. Stop the game. He is offering you a place in his
Drama Triangle to control you and to obtain power over you and over all that will listen to his "story". He is engaged in emotional blackmail and manipulation and that is not what friends or Brothers do to one another.
Don't give it to his game. Accept that he doesn't see that he is not one the level with you, not being upright and is being immoral in his choices and expectations. You deserve better and should demand it.
If all that you say is true, you have done NOTHING WRONG, other than allow yourself to feel unnecessary guilt over all this.