Why am i dreaming of my ex girlfriend?

Seems like you've figured things out yourself. You really do love this girl and it's messed up how she things you're doing all these things that aren't even true. You're seeing her in your dreams because you still think about her even if you try not to you do; the smallest things or what people say or do remind you of her; and you're mourning still. You need to grab ahold of things, pick yourself up, and move on with your life. The best thing that will keep you occupied is school.