Kermit,
Broken hearts heal. They do. You don't believe it when you're hurting, but they do.
And as for your fear of being alone...? If you become the person you would like to spend the rest of your life with, you won't be alone. And if you are, it will be OK. I, like you, have put way too much stock in what others (mates) can do for me. You keep walking, keep feeling, keep working, and things will fall into place.