It is good they want to see you sooner rather than later, as you will be stressed until. The conversation is done. I'd recommend reading the article on Helping Someone Leave on jwfacts.com, so that you are prepared to put the conversation back on them. The onus of proof is the person making to outlandish claim that they alone have truth. Then you can briefly explain how each point they make is inaccurate or a logical fallacy. There is also an article on Logical Fallacies on jwfacts that briefly explains why many of the pointa they will raise are based on poor reasoning.
It is unlikely you can change their point of view, but it is liberating to be able to show you have made an intelectual choice and it is them and not you that needs to explain themselves.
They may be coming to tell you they will hand your letter to the elders if you do not recant, and they will then shun you, so be prepared for how to react To that.