Einstein is a fuzzy haired crackpot - Nikola Tesla
All the dimension are an illusion.
However, these dimensions, east-west, up-down, past-future are what help us delineate, separate and focus upon what we wish to do with this life.
So, although these dimension are an illusion, on the flip side, they are very real.
They are "reality". And you need to work with them as they are.
If you want to, you can minimize all dimension into here and there.
The stuff you are working on is here, now.
Everything else is somewhere else, some other time.
And, you can change the past, just as easily as you can change the future.
Which is to say, changing the future is quite hard. You have to focus on creating a new, better future. You have to learn new thinking habits. And those lead to new choices.