You say he is seeing your effects in instagram. Pray tell, are you posting the effects with their real name; or if you learned them from youtube are you posting them under the name by which you learned the effect? If so that needs to stop. The other question I have is why post your effects on instagram? You say he is a nice guy but it sounds like he is not nice or has some real self esteem issue by not letting you have your moment in the spot light. You need to have a real talk with him about this. Tell him it is impeding your friendship and if he keeps down this road you will be forced to end the friendship. Also block him from your videos.
Then there is the option of just not performing when he is around. When someone ask why, do not call him out by name. Simply say, in your own style, "I'm sorry, for there is one among you who feels the needs to spoil the wonderment and joy people experience while watching my wonderful illusions and slight of hand. They feel the need to tell everyone how the prestidigitation done... And for this reason I can not present my feats of legerdemain. Perhaps a later time."
Then do what Craig said kick him right in the baby maker.
PS.I see William has given some of the same advice while I was typing and putting diner in the crock pot. Teach me to multi task.