Am I just wasting my time thinking about her when I should be moving on?
Yes.
Destroy everything you have the reminds you of her. Destroy her phone number, her pictures, her letters, her gifts that she got you. Burn/trash all of it. You are living like a sick man inside of a vial of disease. You aren't going to get any better until you separate yourself from all that is her.
In never really gets a lot easier, but the more you subject yourself to thinking about her and seeing things that remind you of her willingly, the longer it will take.
Hell, I have had girlfriends from 8+ years I still think about quite a bit. You are only human. Closure is something we never get every time in life. But you are only hurting yourself the more you obsess over the situation.
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