Accept that you are dumped, unfortunately. Make him clear that after the long path you have walked with him, you cannot stop at just being a friend to him. He has to decide between marrying you or leaving you forever. Your nature will never allow you to be happy in in-between state. Breaking up may leave you in pain but with the passage of time you should come out. Do not feel guilty about good time that you have passed with him, rather enjoy those moments in your memories. Do not try to forget him or to drive away his memories. More hard you try this, more pain and helplessness you will feel. Remember forgetting is an automatic process, you do not have to do anything; time will do the trick. Just go ahead in your life, may almighty bless you.