The sentence you wrote is perfect, and insteed to what Henry says, the part "que estudió junto conmigo " is perfect, because "junto conmigo" can be used in this case. It's not bad "que estudió conmigo ", because it means the same than the another phrase, but in this case both could be used within your sentence.
And about "le" and "les", your sentence uses "les" because you are talking to several people, therefore it's plural, and the plural wya of "le" is adding it a "s", and then it becomes "les".
I hope I'd helped you!