Losing love is always going to be painful; but by going through the grieving with self-reflection we can get more capable of dealing with it. Since our society allows serial love relationships, we might as well learn about everything involved in its cycles. Every big emotional change in our life offers a chance to learn something valuable for use in our life, and what you've been given is one of these times. You don't have HER anymore, but you do have yourself; and you can learn to love yourself more by taking care of yourself in new ways now (as Dr-A-Green has offered a few). I've mentioned doing and appreciating things you love, because the greater reward in love relations is LOVING, not being loved. And you can turn now to other people and things you love--nobody can take those away from you: especially things and people of beauty and excellence. Make a list of those things and people, and then put some on your agenda to cultivate. You have good people around you already. By focusing on things of beauty and excellence you can relearn how to express&experience your love without needing a person to direct yourself towards. This is a habit that much more mature people get better and better at (reading, drawing, walking, exploring, meditating, etc.). Loving hurts a lot when you're suddenly rejected; and this is a path toward regaining your balance. Keep a journal of what you're loving around you as a balance for your feelings during your grieving now. And observe also what's going on inside of you, as a commitment to gaining appreciation for your own inner being and greater capacity to use your own mind and emotions for your own benefit.
Being dumped is a helpless feeling, so it can be helpful to seek understanding of what happened and why--and to learn what you can for the next relationship. I taught a Psych of Relationship class at Embry-Riddle Aeronautical University for 21 years, and the textbook I wrote has a 15page Appendix that explains a lot about recovering from the breakup with dignity. For over 15 of those years I gave students the option to write about their relationships (after first describing their parents' relationship and each parent's effects on them), about the turning points, the ways they flourished and withered or changed in each chapter of their loves--as a way of learning about themselves and preparing for more reflective and conscientious relationships in the future. YOU can do that now, as a commitment to getting ready for your next relationship and giving yourself a better experience base on which to operate in loving. If you would like to do that, I'll send you the instructions I wrote for those "Relationship Resumes." And if you also want to get extensive comments by a Marriage Therapist of 40+ years (whose second doctoral research dissertation was on the love lives of adult children of divorce in my classes), you can send it to me when you're finished and I'll take the time to comment very carefully.
I'm not suggesting that you Should do this, but just that you Can take advantage of your present suffering to create a significant "learning opportunity" for yourself. I don't expect that you could create such a relationship-history in a week--esp when you're in the early weeks of grief. I'd expect it to take you a month or two. But I'd be glad to help you understand by starting from what you're writing and adding to that from my decades of experience with people in your stage of life.