Well, well a lot of contrasting opinions.
Now let me tell you how it really is.
EX's do come back. All the time. Give me an ex I've dated before, if I really wanted to I could get her back. Why? Because the behavior of women becomes a pattern. Mold to the pattern and she'll fall back in your lap.
But the real question is, do you really want an EX back in your life?
9 times out of 10, nope.
The reason why you think your girl left you is irrelevant. She's been planning this for a little while (I know it's tough to suck down) and your outrage gave her enough 'public' reason to do this.
I say 'public' because a chick almost NEVER reveals why she's really dumping you. The real reason could be:
1. you don't turn her on anymore
2. she wants to be single (aka get some strange d1ck)
3. she's found someone else to swing to (branch swinging)
These are private reasons. Women most often give 'public' reasons so she doesn't come off like a slvt. Her public reason for you was that you weren't treating her right and come on.. PLENTY of dudes don't treat their GFs right and hold on to them for a LONG time. This is clearly not a leading cause to why women get rid of their boyfriends.
So we come back to your case. For one of the 3 above reasons, your woman has decided to leave you. Either that or she is pulling a powerplay in which she hopes that you'll change your behavior and beg for her back. However it doesn't sound like this, as she's become pretty nasty with you.
By nexting you she disrespected you and pretty much told you who wears the pants in the relationship. Moreover, when a woman totally changes her attitude towards you and treats you like a piece of sh!t, she usually isn't attracted to you anymore and knows she can get away with treating you like that.
So enough of the past.. let's talk about the future.
Could you get this chick back? Absolutely. Is it in your best interest? Probably not.
Sure, you could go weeks without talking to her and she'll probably find some way back into your life, but why would you want to do that? Now that she's shown you that she's capable of getting rid of you, who knows what she'll do next time.
I mean hell, Friday she was telling you that she loved you. Look how quickly things change. Women move on emotions, not logic, so therefore their feelings change all the time.
Sorry to hear about your loss, but understand many of us have been through this. Move on accordingly.