I'm trying to model the motion of a block sliding off an edge for a platform game I am making but I am stuck please help!

Here is the concept:

http://imgur.com/CTf9GZq
Here is my work so far:

http://imgur.com/MBOFh9k
What are the equations of displacement and rotation in terms of time? x(t), y(t), and theta(t) for the rigid block falling and sliding off the edge?

I have found the accelerations ax and ay in terms of theta and theta in terms of x but don't know what to do from here to get it in terms of time.

ax = gcos(theta)sin(theta)

ay = -gsin2 (theta)

theta'' = 12gx/(h2 + L2)

Since theta'' changes as x changes and vise versa I don't know how to decouple the equations to solve this analytically. Any ideas?