I had the same thing happen to me. Luckily everyone at the Companions kept him in his place. I cant remember if or how I got him to stop. Think I just left for a few day.

I had this happen I killed a noble and his guard on the road and I got a bounty in whiterun. I killed the horse and it went away. After I went back to Whiterun he started attacking me, and the stuff you described happened. I just reloaded the save before I killed the guard and went into whiterun and everything was fine.

He attacked me after I killed Faendal.