Please do not do anything rash. When emotions run high, we do things we ourselves would not advise others to do. Take some deep breaths, consider the other people who know you, love you, care about you. How will they feel if you harmed yourself?
When you lose your self-control and dignity, they'll see it as victory. Don’t let them gloat. By being strong, you can remain unaffected, independent of their attempts to assume victory. You defeat the cult mind by not playing their game.
Allow him his mistake. If he is smart enough, he will learn from it in his own time. If you love somebody, you shouldn’t make them do things against their will.
They say the best revenge is served cold. I will go one step further and say the best revenge is the one that happens when you don't even care what happens. It does not burn you up in the process and you can appreciate it with a clear conscience, even if ”nothing” happens.
It seems that you have become obsessed with this. It is understandable, matters of the heart make us feel alive. But that is what BKs want. They
want that you are less happy because you are anti-BK, a kind of proof for them that they as BKs are superior (it's the self-image they cultivate, but BKs are riven with jealousies, politics, ambition, dissatisfactions in many ways - but they’ll never admit it).
I ask that you be the wiser, clearer thinking person that you seem to be. Do not let your wounded pride, your dashed hopes for a future you’d imagined make you now do something stupider and more dim-witted than what he is doing. He is ruining his life with his choice, don’t let that choice ruin yours too.
First serious loves are significant. You explore new emotions, you discover so much about yourself, others, life. But they are called ”first” loves for a reason. Real love grows when given and when received. If he has shrunk, that shows his love for you was not what you thought.
Take a break from all this. Focus on the other things in your life you surely have been neglecting while you have been engaged with this. Gather yourself together.
Engage socially with normal people (non-BKs), spend more time with your friends and family, and (I know this may be hard) don’t keep ploughing over old ground, make a break with the past. Look around, you will see there are other people in the world worth getting to know.
You will never find the right person if you never let go of the wrong one