Sorry for the delay. I apologize for your wait.
Let me analyze few of the things you mentioned but there are so many things involved in a long term relationship that it may not be easy to rationalize everything in short span of time.
There are few things which you know already, but perhaps accepting is not easy, as there may be something which keeps you attracted towards your this friend. He has not been keeping promises and appointments; which is the least expected in a serious relationship. But somehow you ignore the shortcoming and kept going. But once it went over the roof; you mentioned it, which was very normal reaction. And now he is offended.
Actually he never took care of your hurts when he puts you on hold and declines at the last minute and many other things. But the same medicine has been bitter for him.
So my counsel is; do you still want to continue with the relationship? You know that you may be ignored and hurt in future too! If that is worth meeting this guy which has something which you long on. You may make more efforts like going to his office or home to meet him and mend the things. But otherwise you may consider saying it a quit.
The only question for you to answer is; Do you want give it one more try?
Please feel free to discuss it further.
Wishing you all the very best in life.