I sorta skimmed through this but I think I got the general idea. Your ex is insecure and in no position to be in a committed relationship with anyone, you should be glad and thankful she left you. You decided to pick up everything and move for a rebound girl, that was where you fucked up. I really wouldn't be surprised if she randomly contacted you asking to meet up, to pick up some things she left, etc.. This is when you reply with a firm "No, I'd rather not. Take care.", seriously fuck this chick, she seems like a headache. If she comes at you asking to pick up some stuff she forgot, just politely tell her that since she left those things there you were in the right to assume that she didn't want or need those items any longer and that you have thrown them away as you didn't want any reminder of her in your apartment.

What is she going through internally? She just wants attention from guys.

Is she going to come back to you? You better hope she doesn't, and if she tries, firmly deny.

You seem like a smart guy, good job, bright future, you don't need to be weighed down with the burden of dating a girl like that