Well to begin with I can say that memories are just memories and you can't do anything to just forget them ! It's impossible .. Yes they kill us I know that perfectly, but living in the past is an awful thing. 
Secondly, you have to think about your future of course because you can't return the past but your future is waiting for you. You must do everything to achieve your dreams, goals, aims and etc. Be ambitious ! Never give up ! You are your own teacher. Do whatever you want but with love. That's one of the most important things. Do what you love and love what you do. Don't worry about what other people will say, because the majority can't compete with you. Always believe in yourself. If you believe in yourself long enough eventually they will too.
To end up, I will say one thing. Always listen to your heart and everything will be perfect.