where did we go wrong?

i used to have a friend and we were pretty close,we always chat and laugh together,even on the first day we were like omg u know that song too!we also text each other about homeworks. One day we had a fight and i totally lashed at him because he did not tell me a certain information that is crucial about assignment,but it was not serious but he realised it was his mistake and he apologised,i didn;t reply the text message but we made up again and things became normal again,his face was pretty guilty though. Suddenly my friend started ignoring me and treated me like a mere stranger because of his newfound it girl. One day i encountered him and his it girl to ask for an assignment and he totally ignored me,i even heard that girl said"just ignore people like her".the next day i simply shift my sit which was usually next to him as far as possible since i find that if this is what he wanted then fine i don't mind. My other friend said that maybe it's my turn to apologize so i did but it just boosted his ego. He even backstabbed me during a group assignment by not including me in every team work, he also gossiped about me to his newfound circle of people so everyone knows. Before he used to be sincere(or what i thought he was) he looked like an easy going person but oh well i guess not. when i asked if there is something wrong he said nothing. he was being quite a bitch and he likes to middle in other people's business,quite a hypocrite too,he is so fake that he flatter everyone. When we were friends he often just call to talk,he often offer me a ride home,even wanting to treat me,but i declined because i thought i don't want to owe anybody. Then one day he kinda mock me by saying fine it's your loss anyway. after that when we were assigned as a group to copy papers,he copied for others but me,and he always joked about me infront of others,in a mocking manner off course,but i just ignored him because i know that he's just trying to mess with me and i didn't feel infuriated by him like he did because of me. i just think it is childish of him. it gets weirder since we must submit our assignment on a usb so i asked him to bring my usb,i even asked whether he copied my assignment from the usb knowing the bitch he is. he said that the usb is in his car so i asked him to take it,the weird thing is he asked me to follow him to his car just to take a usb so i did and left,then after i got my usb i left him with his car, he is just a show off.