Should I keep trying to get my best friend back?

You say "I just ended our friendship" and he was supposed to accept that. Obviously, he was hurt and bewildered by your decision to do that. Now you have decided that you want your friendship back just the way it used to be. You cannot expect that to happen. It will never be the same due to your actions. He has learned to cope with the feelings that you in him and he has accepted your decision to end the friendship and he has moved on with his life. You have made it clear that you want the friendship back. It is now up to him to decide what to do with that. He can consider the options and decide that he does want your friendship back. or not. The trust will be gone as he will never be sure that you are not going to back out again.