I'm so sorry you're struggling right now!
Please don't be so hard on yourself. You need to keep in mind - you gave several years of your life, your mind, and your heart to this person. It's going to take time for your whole person to heal from that. I think it's perfectly understandable that you don't see yourself being with someone else right now, and even that your fantasies aren't active. You're going through a big change, and your whole self is figuring out what to do.
Nurture yourself right now. Stay connected/nurture connections with your family and friends. Do things that make you happy - take a class, go see movies or concerts, rent a bunch of Disney movies, or whatever. This could also be a time for you to do that "something" you always wanted - a new hobby, volunteering, writing - whatever your heart calls you to do. Maybe it's getting a pet - some sweet little critter to love you and have some companionship at home.
Journaling has been a huge help for me. Maybe getting your hurts, hopes, dreams, etc. down on paper would be helpful for you. Sometimes we all need to take a break and figure out who and what we want to be. Take that time for yourself now!
Focus on yourself and decide what you want to be in 10 years, a better job, better health... let friends come from people who share goals and recreation that appeal to you.... don't try to program for someone else, develop focus on being more yourself.
True friends and hopefully true love will come from going your way. Of course if you become close to someone, hopefully someone who you already know has a lot in common with you, you'll have to be more flexible if you what a long term (life-long, how about that idea, used to be called marriage) relationship some differences will surface.
Good luck, find a better future to your liking.