What is this now?

From the vantage point of experience, the present alone is real.  The past has happened and is just a memory, the future is yet to happen and can only be imagined.  However, if this now is the boundary between the past and future, is it a boundary with width or is it infinitely thin?  If it has width, then there must be a past, present and future within it and hence another now in this now.  There must be a limit to this division of the now or there will be nothing left of it.  But even with a limit, this division must end in a very tiny moment, one that arises and passes away so quickly as to be effectively indiscernible.  On the other hand, if the now is an infinitely thin boundary between the past and the future, in essence a moment without duration, in what sense can it be said to exist at all?  
Whether this now exists or not, this moment is very elusive for sure, constantly shifting as it does.  Can we only "grasp" it as a fleeting memory and pretend that a "now" that constantly eludes us is "present" when it is actually gone?  How can we be "in" the present when it never is "there" long enough?  Yet, it is inescapable:  we are always in the present moment for, after all, that is all there is.