Best way to apologize?

Ad Astra, First of all, you do admit that you messed up when you had a chance to be with someone special but dont beat yourself up because you didn't make the move at that time, you said it for yourself you wasn't ready for a relationship and he should have understood that from you. You said he move to another state, yes by now he probably have moved on but don't be discourage of yourself if he has, it just that at the time he wanted a relationship with you and you wasn't ready, then he felt he should move on so don't hate him for that, all I can tell you if he has just let him know again why you wasn't ready for an relationship at that time, tell him you do apologize for your behavior, ask for forgiveness and if he hasn't move on maybe you and him can reconsider about being more than friends if not maybe buddies. If he is still serious about being with you then he will come back and work it out but if he has moved on ask for apology and see if you can still be his friend and continue to communicate with him. If he doesn't want either then at least if have gotten what you has to say to him off your chest. Just don't waste your time on him so good luck to you and hope all works out well with him.