Just Got Robbed

ok so i called a guy who i dont usually get my stuff from. i got to the stop and called saying "dude is there somewhere i can meet you cos im just hanging around". he said ill be there i saw a call come on a moped and he came and said what you doing?i said waiting for a friend. he said give me some money or ill stab you. i said i aint got none he tried to search me i then tried to ride my bike away and said im going to meet some one. he then then tried grab me who i road on. he road up against me and tried grab me and knock me off in the end i got to a public place where i couldn't get stabbed or he would he seen. people saw him trying to rob me but they did nothing. in the end i ended up giving £20 to him cause i "broke his bike" when i picked him away from me when he was trying to get me. 
\nso my dealer calls me 15min later saying "you ok? did that guy on the bike rob you?" i said yes and explained what happened. he then replied the same guy tried asking if my dealer was going to meet some one ect". i said to the dealer you should have called me or text me to go somewhere else. this wouldn't have happened if i wasn't hanging around in a spot.
\ni know who the guy is  thats the crazy thing i played basketball with this guy like 2 months ago and he was talking to me and was actually ok. i recognised a tattoo on his neck thats how i knew who he was. i dont know if i should tell my parents what happened or not. no one knows what happened yet now i dont know if should smoke weed any more and the fact the guy did that dont mean he will try it again.