I miss the person he was before his accident

I don’t know if anyone’s had experience with traumatic brain injuries but I’m just feeling really down right now because I just miss the person before the injury. Don’t get me wrong I’m happy that he survived but I’m just sad because it’s just not the same. I’m left with a shell of a person. He’s depressed and angry. He’s mean, he used to be the sweetest person ever. I know he’s battling some demons but it’s just so hard. I’ve fallen out of love with him because he’s just not the same. I feel guilty and I don’t know what to do. I can’t fix him.