Find things in your life that you need to focus attention on, and that you really love doing. Creative things where your attention needs to be on them are good. Be with your feelings. Grieving can't be rushed. You're not weak for feeling pain, you're sensitive. Only sensitive people can be compassionate, and really help others, but they also feel pain a lot more strongly.
Write a list of every quality you would want in a partner. Then go back to that list and honestly answer if this relationship gave you those things. If the answer to all or many of the things you want is "no," then it's not that person or that relationship you wanted, but instead it's attachment breaking that’s rough, or a strong reaction to rejection, or some other thing that's pulling you back toward something that you really weren't all that happy in when you were in it.
Let go of the “could have been.” If they’d only been nicer, or done this, or appreciated that…well if they’d done all those things, they’d be a different person. You have a lot of love to give, and you directed it toward someone who was unwilling or unable to give it back to you. That doesn’t mean someone else will be the same. Though you can’t even think of someone else now, it won’t always be that way.
It’s difficult to find your legs to get up and move on when you feel like you’ve been knocked down so very hard. But once you do find that love, that strength, inside of you, you won’t ever be knocked down like that again. This can be the hardest, but ultimately, the most rewarding, strengthening time of your life. For now, enjoy the things about being single that you couldn't enjoy before...whatever those things may be. Do things that you want to do, when you want to do them, and learn to love and feel complete in a single life. Learn to love all the great things that are unique and wonderful about you, and really discover who you are and what you really love in life. Whenever the time is right for a new love, you will be whole, and will have so much more to offer. You will have found you. Trust.