Her job, her new coworker, you. These are reasons to act the way she did, but they are not excuses. She treated you like a turd sandwich and is trying to blame it all on you? It doesn't take a psych major to pull these low-blow moves, it's typical human response when they do not want to accept responsibility for their own actions. What do we do? Blame it on somebody else. She lied to you repeatedly and whether you loved her too much or too afraid to kick her to the curb, she capitalized on that fact. You let it happen a few times, you are equally responsible for this happening again.
It's important to know what they are doing as opposed to what they are saying. No matter how much she says you are amazing and I love you, if her actions don't show that, I think the actions are pretty indicative of how they feel. When we are so emotionally charged, our logic and intellegence plummet and it's difficult to notice these things. Open your eyes to this. You may love her, and it hurts to lose somebody you had for three years, but if this is what she wants, it doesn't matter how you feel. It can't happen if both parties aren't interested.
Don't beat yourself up, how she feels does not reflect your self worth. If you believe you are a good person and have alot to offer somebody, you will find somebody that will accept the love you have for them. Or they will find you. It will work out at some point. Not that you can think of somebody else, but you have to try and keep telling yourself: this is it. This is what she wanted. She misled you until she had her new guy lined up. That's being dishonest with how you feel. It's wrong. It's immature. She rather try and soften the blow instead of being honest and in this process, prolonging the agony. She doesn't know better, she thinks this is the way to treat people. Clearly it isn't. Try to understand that currently, right now, this girl cannot be the one for you anyway. She needs to do some growing up on her own and she won't if you are there to be her crutch through all this.
Waking up next to a beautiful girl,
Step outside and say hello to my beautiful world.