Sorry to hear that bro, and I have gotten through one longterm breakup and a few shorter ones. A lof of cheating and mental abuse towards me, so pain is something I know a lot about.
What I can tell you is that:
- You will feel pain and pain is allowed to be felt. Don´t fight the pain, don´t ignore the pain, let it wash over you naturally. Your mind and body will decide when it´s enough and it can take time, but the more you fight it the worse it will become and the more anxiety it will cause.
- It´s not weak to cry, do that when needed, just remember that sorrow is harder to beat than anger. I would recommend you choose the anger path as it will strenghten you faster. Not anger towards her and others, that is resentment, but anger towards not earning enough, not studying enough, not travelling enough, not lifting enough. Anything that makes you productive.
- Be open-minded, past is past and next one is not the same person as the old, give yourself and her a chance when you´re ready.
- Rebound can absolutely help, but imho NOT s*xual reabound. You need someone who can fill a roll of mental release rebound. Emptying your sack does nothing but fill you with regret, have someone you can laugh with or talk with before and after. Call that a temporary girlfriend or friend with benefits, but "friend" is the keyword.
- Talk with a mate you trust and who can be honest with you. Who knows what you should hear, not what you want to hear. A man, not an ass-licker.
And if you need an anonymous person to talk with, I and many other brothers are here for you!