One of the worse situations in life that someone can be is to be in a rapidly ending marriage.
It's all the worse if that someone actually doesn't want the marriage to end - it's impossible not to be reminded of the good days wherever you look.
Like I said in the title, I have been in this situation and want to say I feel for you.
But it's not the time to be sad and cry - it's time to cheer up, because I turned the tides in my marriage and have saved it from a divorce and will help you.
My marriage is very firm and healthy now! The reason  I said cheer up is that doing the opposite will harm your marriage even further.
It's not possible to be happy when your marriage is ending, but it's possible to retain control over yourself so you won't go desperate and try the wrong, desperate things.
Such things would be to try to show how weak and sorrowful you are to your spouse, in hopes of a reunion.
This makes you look pathetic and makes your spouse even more fed up with you, so you should avoid them like smallpox.
Saving your marriage needs careful consideration of the human psychology.
The reason the "Look at me, I love you so much that I am very desperate right now" stuff will never work is that they make you look pathetic.
And they make you "easy to have".
Remember that people want what they CAN'T have - this is incredibly crucial to your marriage saving efforts.
This is why your first step in saving your marriage is to stay emotionally balanced in this harsh situation.
Do not cry, at least not in front of your spouse.
Know that this first step (which is equivalent to saying "calm down") is an absolute prerequisite for the next step: Saving the marriage.