Fault
He wanted to hate Moira. He wanted to hate her with every fiber of his being.
He is not selfish enough to give her all the blame for what happened. He was the one who paralyzed Charles. He was the one who diverted that bullet's path from its original target (Why why couldn't it have just hit him instead...) and into Charles.
His most precious Charles, who was only trying to help. Who had only ever wanted to help
It was Erik's fault. It was Erik...
But the fact remains that had it not been for her, there would have been no bullet to deflect. There would have been nothing to ricochet into the back of the one person to ever believe in him, to accept him as he was and ask for nothing in return. The first person to show him that he was more than a weapon built out of anger and hatred.
It was her fault. Her fault her fault. But it was his fault. It was his fault and her fault and Shaw's fault and the humans fault and her fault and his fault his fault his fault!...
But even so.
Even with all the hatred bubbled up in his chest, he can't hate Moira. Not as much as he wants to.
Because despite her role in hurting Charles, without her, he wouldn't have known Charles at all. And regardless of that voice in the back of his head whispering how much better off Charles would have been never knowing him, that is a thought he cannot bear.