My man thinks that I'm cheating on him with his friend What should I do he gets mad every time his friend talks to me or when he touch me

Don't talk to the friend or let him touch you.

Sorry for the simple answer but with all that you provided here for us to help give you an answer, that was the best I could come up with.

A good relationship has to have honesty, respect, and willing to talk about anything. If you both can't talk about this, without him not believing you, then something is wrong with your relationship. Sounds like he is very jealous; and that is not a healthy sign. Good luck.