Dude I'm so sorry, I like your posts and I didn't know you're going through all this.
You know it's crazy to take advice from strangers who know only a few paragraphs from your story, but based on that alone, my opinion is that you CAN do MUCH better. You know that you have to let her go.
You're young, smart and you seem like fun. You've got a bad patch ahead, but keep telling yourself that you'll get through. The one day you'll realise you are.