Of course there is sideways time. We experience it as a moment having greater “depth”. Depending upon whether streams separate or converge, each moment we may be several people or a single person experiencing a moment of greater depth. During those moments we have the option of continuing in linear fashion or availing ourselves of the other directions opened up by the greater depth of the moment. Unfortunately when we remember these moments from a later moment that is linear, the depth is projected upon a single line and the depth of the moment is, in retrospect, flattened.
A linear present can neither remember nor look forward to a moment of sideways time.
And that, my friends, is the cause of oh so many problems!