Should I use "this is" or "that is" in the following sentence?

Question

If I lie to you, I'll lose your trust forever. This is the last thing I want.

If I lie to you, I'll lose your trust forever. That's the last thing I want.

What's the most appropriate option? Or maybe they are both correct

Answer 1

That is much more likely than this.

The reason has little to do with whether it is near or far, as suggested by Joshua.

When we are referring to objects or places that are physically present, we do indeed prefer this for closer objects.

But when we are talking of things that have only been referred to linguistically, we usually use that, especially in ordinary speech. Using this sounds stilted, unless we are setting up an opposition between the statement or reference we are referring to and some other statement or reference.

Your first example with this suggests that you are going to go on and say some alternative.

Answer 2

I think "that" is the most appropriate thing to say.

My reasoning:

1. You are supposed to say "this" when something is close. So if something bad has happened, you should say "I did not want this to happen."

2. You are supposed to say "that" when something is distant. So if something bad hasn't happened yet, you should say "I do not want that to happen."

Look at what you said:

"If I lie to you, I'll lose your trust forever."

They haven't lied yet, which means that "that" is most appropriate.