I've prepared a quick example to show how this can be done. I'm not sure how you have your object moving, so I set this one up to move at 100 pixels per second along the X-axis and to use the sine behavior on the Y-axis, but the same concepts should apply regardless.
Sine Facing example
There's a small bit of calculus involved to get what we want. We start off with our position functions for the object, which are as follows(not Construct 2 expressions, but close):
X: InitialX + 100t
Y: InitialY + Magnitude * sin(CycleAngle)
Take the first derivative to find the velocity:
Vx: 100
Vy: Magnitude * cos(CycleAngle)
Now that we have the velocity, we can use the angle() expression that I outlined in my original post to find the direction of travel. Note that with the sine behavior, Sine.CyclePosition is just the normalized angle used when calculating the oscillation, so we multiply 360 to turn it back into degrees.
As an additional note, please try to avoid so many posts in a row in the future -- you can always edit new information into your previous post.