I'm sorry. He's actually pretty pathetic for this. He's projecting his failures onto you in an effort to make himself feel better. Shame on him for trying to manipulate into thinking its your fault. You have vested time in him, that's why you are holding on. This guy is completely out of line and takes no responsibilities for his actions. He's looking for some other person to bolster him and help/force him to do better.
He needs to be out, and he doesn't need or deserve your loyalty. That was the most pathetic passive aggressive break up note I ever read.
I'll summarize. "I love you, I haven't accomplished anything. I want to blame you for not pushing me. You didn't push yourself. I'm getting older and this is a dead end. goodbye.... if I get older and nobody wants me I'm going to hit you up"