Hi.. I understand the confusion your going through but there are some facts you need to face dear. From what you have told us about your relationship with this man, I get that he has been in your life from quite a long time. That having been said, I think you need to realise that he doesn't want to commit to you. The last time he started dating someone is proof enough that he doesn't see you as a romantic interest.
I suggest you do keep distance from him and follow the no contact rule strictly. It will be hard but it is for your own good. Distractions are a great way to stick to the NC rule. Keep yourself occupied and slowly you'll be able to get over him.