If someone is meant to be in your life, they will come back to you. You can try to move on all you want-- They'll come back if they're meant to, and the timing will be right.
You can try to hold onto someone all you want, also, but if it's not meant to be it's just not meant to be. Go with the flow. You'll figure it out.
Throw away all inhibitions and fear. There's no use being afraid when risks are meant to be taken. You might as well just go do the thing. You'll never know if you don't take the chance.
People will hurt you. By accident, usually, if they're good people. Good people don't hurt others on purpose, without a valid reason. Learn to understand this accidental hurts, and forgive them.
Remember to embrace what you feel. All of it. It will make you stronger if you can stand up from the negative feelings once they are felt, and embrace the one you love within the positive ones.
You don't have to be alone all the time. Let them in, I promise it's okay.