Rotating the end point of a stroked line?

I am trying to rotate the stroke on an end point of a line that I've drawn.  Is there a way to do this while keeping the line in tact?

Before:

Desired Effect:

Notice the top point on this line.  I've faked the rotation that I'm talking about.  Is this possible to do without destroying the line, adding a white element above it to look like I cut if off, etc.?

Thank you