They saying knowing is half the battle.

What it sounds like is, right now, you are going through a grieving period.
Any time we lose something we really like, we grieve it's lose.
It's normal and, most times, needed in order to grow from the experience.

During the grieving process most bets are off.
You can cry and scream and say you didn't deserve it.
You can wish it never happened or spend most of your time imaging all the ways you could have better handled the situation.
It's ok to feel sorry for yourself during this process.

But it also can't last forever. We are human and we make mistakes. That is how we learn.
Also, we don't always learn the lesson the first time around.

So when you feel you have sufficiently grieved out all the pain and regrets, you are ready to move on with one more life lesson under your belt.

It all really hinges on what you do today that will make tomorrow a better day.

We are not the same people we were yesterday.
The real question is can we be better tomorrow than we are today.