You can't make this feeling end. I don't know how long ago it was that you two broke up, but if you still feel like you are not over it, don't rush it. There is NO friggin' time limit! Yes, she has moved on, and you are still in the pit, but do you know what the odds are of two people breaking up with each other, and getting over it at the same time? They are quite small, if you don't count the people who are mutually too immature to care.

And even when you're over it for a while, seeing her with her first new boyfriend does bring back sparks of loneliness, unless you are seeing someone else also. You just have to ride out the wave, and let time do the healing. You mentioned poetry. How about writing some material that describes your pain, for a change? That might make you feel better. Hope this helped.