Thank you very much for your input!!!
Wow.. this is not going to be an easy task I assume...
This photo was taken before the drywalls were up..
the room behind is a sunken laundry room..
this is where I want all my tiles.

the wall sits where the PVC pipe is going across.. right between the last floor joist and the sunken area.

The last floor joist - one end is supported by the I-beam and the other end is support by the foundation of the house..
Am I safe??
Do I still need to put up a brand new cement wall??