Irisha, the only advice I can give you for closing down this channel of connection with this individual is to find a way to with-draw your attention from it.
I realize this is hard for many people to accept, but nothing can assert itself into your life experience. Awareness of what is, maintains the connection to what is. This is why techniques such as visualizing a shield or things of that nature are oftentimes not effective. Inherent in the visualization of protection from that thing you do not want is the activation of the vibration of it in your experience. I know its hard -- especially when it is constantly in your face at the moment, but if you can find a way to ignore it for a consistent period of time, you can begin the deactivation of that reality in your experience.
The above comment goes for any type of "healing" as well -- it's like the difference in vibration between "gratitude" and "appreciation". Gratitude is like looking at a problem you just got away from and saying, "thank god I'm not dealing with THAT anymore." In other-words, the attention to that thing you are glad you got away from is actually the beginning of the RE-activating the vibration of it, whereas appreciation is a more "free" and pure vibration because you are just loving and accepting what is, and that is the focus of your attention.
Thoughts -- your focus of attention in this moment -- is the invitation for this thing you do not want. It won't go away immediately, but the more you can ignore it, the more distant it will become over time, till the connection is broken.
If I were in your shoes right now, I would try to pretend that any thoughts that came from Mr. G, were not real. Ascribe as little reality to them as you possibly can. Ascribe as little importance to them as you possibly can. Imagine that they are simply aspects of an idle daydream, and if they occur brush them aside as things of no importance. And then focus on something else. In fact, make it into a habit that any time you sense any input whatsoever from Mr. G, to just immediately find something else to think about. If you can succeed in turning this into a second nature habit, it will de-groove the circuit of consciousness that is making this reality of telepathy flow even possible.
Thought channels have a kind of momentum, and consciousness always follows the path of least resistance. At the moment, your path of least resistance is the thoughts you have been thinking on a regular basis. This constitutes the current momentum of your thought. These are channels of thought that make it possible for that telepathic communication to occur. You need to make new pathways of thought, and then make those roads of thought your dominant and second nature thoughts. It won't be immediate, but over time this trance Mr. G has created will simply lose coherence as you add more and more thought elements and make this trance of thought flow unstable.
One other option is to find a competent and sympathetic hypnotherapist who could close this channel of communication down by working with your subconscious patterns of behavior. Hypnosis can be surprisingly effective with things of this nature. The only trick is finding a hypnotherapist who will be sympathetic to your plight, and not just assume your schizophrenic.