This proves that he had never loved you but under the name of love, he was maintaining relationship. No sooner he got his girl, you are out of his priority. You have to accept this in first place. You do not have to do anything to forget him as forgetting is an automatic process with the passage of time. If you remember the time spend with him, take it easy. Happy memories are always keeps on coming to your mental surface and you do not have to do anything to keep them away. Just try to shift your focus to your career and other relations otherwise you will be left with your emotional baggage. Decide to move on with a life rather then to freeze with painful past.