Not too long ago I was a first year . These conflicts will happen at every stage of your career . You will have coworkers who you hate and you will have clients whose stupidity will defy reality . It is part of learning and as a first year that is one if your prinary responsibilities to learn . Reading your wall of text highlighted a few times how you SHOULD have done something differently than you actually did . That is called learning and developing worthwhile experience . Put your head down , stop being a little shit no matter how big an asshole your senior is and put that experience to work . Dont get me wrong , I do not advocate seniors who treat first years like shit . I actually dont support anyone being treated like shit . But this is the real world . You need that senior more than that senior needs you . Dont fret . It is one engagement and you will find multiple opportunities to prove yourself to your current senior and manager and also others . Just be smart and realise that there are some battles worth losing and you dont need to pipe up all the time to correct all things which you deem to be wrong . You will face such challenges in any work environment . Such is the nature of an office job . Hope this helps . Good luck .