4 years story: she dumped me. Now she's coming back. Tips from previous experience?

[SugarGuy]

Hello broken heart.

If you read this, it means you got through this situation or you're getting through now.
I will not tell about my story, the title is enough. I do just add we were Ying and Yang, it was amazing true love and we wanted to build a family soon; but that's before last summer.
Than she had some doubt because of a guy (which more "similar" to her) and I wanted to broke-up; she didn't do anything with this guy, it was a platonic thing. But she seemed to be sure of the choice.
If needed I will do it in the very single detail. I just want to get some advice from experienced people who got the same. My questions are:

- What did you do? Did you take her back?
- Is it working now?

Actually I have another girlfriend and my ex is alone now (she went abroad right before the broke up and she didn't meet the guy anymore, she is alone since we broke). After 4 months she texted me saying se wants to come back, she will do the best to take me back and the typical nice things, you can imagine.
I just want to know if it's possible that this kind of "unreliable" person can change after this experience and I could trust her, or else I should definetely don't give her a chance because unreliable persons cannot change. Only experience can answer this question. And I'm here to learn, so please, teach me

Love is worth more than a million, so thanks for your answers!!!

[Blees]

If you still love her your ready to risk. If you don't have that kind of feelings for her don't bother.

[SugarGuy]

I know that it's up to me to decide, and to be honest I still love her. But my question is: is that a "rational" choice? To be more precise: a person like her who changed her mind after 4 years and now is changing again, is a kind of person that we could consider "forever undecided" or something like this? My question is more psychological...I would like to know if I can address her to a certain person group which is better to forget. Could also be a stupid question though