Just mourning the life I once knew. You live with each other so long, you get used to them just being there. Took a lot of things for granted. Took everything for granted. Felt like I was sleepwalking and now just waking up.
Break-ups do that. There's always a point after a break-up when you second guess your decision. Because you miss the other person or are suddenly reacquainted with the feeling of being alone. And it kinda terrifies you.