Is it healthy to consider my ex "Dead," and out of my life forever?

I somehow don't really actually get the sense that you have mourned his death as you suggested. In fact it really sounds as though you are pretty well fixated on what he did or didn't do over the course of your relationship. You say he was bipolar. That means he has a mental health problem. I don't really mean to sound rude but what is your reason for putting up with his treating you like garbage? Whatever his reason for acting as he did, whether he just wasn't being adequately medicated or was being given the wrong meds, only you decide how you will allow people to treat you. So you let him treat you poorly and now you are still hanging onto the feeling. Stop it. Stop letting him do this.