LOVE? A strange feeling. A kind word from her and u feel invicible, then the next thing u know your life is a misery. Actually there's nothing more powerful... either makes u or breaks u. When it's over, yeah... it's ur whole world that crashes... nothing else matters anymore.
I've been there, Noir, many have... each one among us broken hearts has felt exactly like you describe yourself these days... no taste for anything, dark thoughts all day long. You want to end it all. You don't understand... what happened? Not her, can't be. You start questionning yourself... i should have done this, said that... maybe... well, guess what? It's pointless.
The only one suffering here is you... we're NOT meant to live in emotional pain, never... this existence is too short. Chase your negative thoughts away RIGHT NOW. You'll heal anyway... so why wait anymore? It's now that you must recover... and that implies FORGETTING HER. She betrayed u... therefore she's not deserving all the credit u still give her... not worthy of ur love, make no mistake about it.
You may say, actually that might be what she told you, that it was an error on her part and she regrets it badly, wants to give ur couple another chance... well, I don't know... she may be sincere. BUT even if she is and you're willing to forgive and try again cos u've never ceased to love her, you have to RE-BUILD yourself first!!
In this moment, down and blue all the time with a lost appetite for life, you're not desirable anymore... neither for her or someone else.
Women like mentally strong men... they hate cry babies. Of course you're not one; you're just awfully sad. But the way a girl will perceive u is like a weak dude... and that's not appealing. At all.
Your only chance to conqueer her again if ever it's ur intention, is to get away from depression and start existing again... when she sees you're ALIVE and become distant, that's when she's gonna get attracted again... fearing you might not be belonging to her anymore will hurt her ego, and her innate possessivness will make her do efforts to seduce you again.
So first step first: stand up and fight. For her or someone else. For you first. No time to waste... no one should be able to break u to pieces like that... don't let ANYONE have that much power on you.
Be strong!! There's no other way around.