I have a statutory decloration of ownership stating that I own 50% of the home, my name is not on the mortage?

it is the primary residence of myself and our 5 year old son. The father of our son is the other co owner and has never resided in the residence. Does he need my permission to sell the home and what happens to our residence if he files bankruptcy will I loose our home. Will I loose the equity I have invested in the home?