Get your ex girlfriend (or wife) back

The following is not to be intended as legal or psychological advice. I'm not a lawyer or a psychoterapist. This is only a shared life experience.

If you're reading this post chances are you have just heard the words "I don't love you anymore" from your (ex) girlfriend. Or maybe she said she needs "time for herself". Maybe you were living together and she left the house, or asked you to leave.
You feel lonely and depressed and you don't know what to do to get her back. If you feel confused there is only one thing to do in your favour, not to make things worse first of all. It looks like a simple thing but you will find it's really, really hard to do.
Right now you feel like you should contact her, tell her how much you love her, that you will change for her. Maybe your friends are suggesting you to do similar things. Maybe you have already sent her flowers or love letters after the breakup.
I've been in your situation before, multiple times, and I've done things like that. I texted her begging to get me back. Phoned her with a trembling voice trying to understand the reasons of the breakup. Sent dozen of roses and love letters. Well, as you could guess nothing of this has worked, actually it worsened the situation. You could get at such a point where your ex threatens to call the police, or at least she blocks your number and account on every social media.
I didnt't learn much from my previous breakups, but I did learn a lot from my last one. It hurt me so much that I spent more than 3 months in grief, not knowing what to do, and doing only things that worsened the situation. If I can compare it with the loss of my mother, which I suffeded when I was 16, it has been 10x as hard. This was because I was living a very stressful moment in any part of my life: work, wealth, family members, finances. My only anchor was my wife, until she went away from home with my two children.
I was going to a psychologist when she left, and he told me (for 100 bucks per hour): "there is only one simple thing to do if you want her back...don't you guess what it is? You have already done it in the past...NOTHING".
I didn't really understand the meaning of this sentence...what is exactly NOTHING?
I discovered later that it really means NOTHING, NOTHING and more NOTHING.
No texting to her, no calls to her, no flowers to her, no letters to her. No contact with her at all. Even better if you don't talk about her to anyone, even your intimate friends and relatives. Act if she never existed.
The only contact you're allowed is the one related to the children, if you have children with her. And don't try to do or say something more with this excuse, you know what I mean, and she will feel it in a nanosecond if you do that.
For how much you must do NOTHING? It depends....
In fact, I found that NOTHING isn't the only thing to do. During the NOTHING period you also have to do the following things, otherwise when she gets back things will worsen again:

1. think about the fact that you want her back. WHY do you want her back? Do you really love her? If not, you'd better move on and find a girl you love. Maybe you want her back just because you feel out of control being rejected. Or maybe for economical reasons (if she is your wife maybe she will get your house, and you will have to pay for the children). These are not good reasons to want her back, believe me you will live better without her if you don't really love her.
2. Do you really want her back? Or did she make a decision that you weren't bold enough to make?
3. Improve yourself. Improve every aspect of your life FOR YOU, and not for her.

When you will have answered to questions 1 and 2, and you feel good with yourself having done number 3, you will have anough clarity of mind to stop doing NOTHING, and ready to do something.