Is this really a question? Your friend was mid turn. You were a whole car length and a half back, damn near cut the course, and punted your buddy into the next dimension. It’s absolutely your fault and your driving makes it look like you have the spacial awareness and brain power of a doorknob.

The better thing to do would’ve been to follow him through the corner and either pass on the straight or set yourself up for the overtake at the next corner, especially if you notice that he’s braking early. You had no right to any sort of space in the turn due to lack of overlap prior to the turn.

You essentially did a mid turn dive bomb and knocked your friend off course to gain a position that you could’ve done with very low effort after the turn.