K.
C.,
I assume you are aware of Canterbury in Desoto. Maybe that's the closed school you were referring to.
Also, Ovilla Christian School in the Red Oak/Ovilla area is a decent private school, but it's Baptist.
Trinity in Cedar Hill is an Assembly of God school that is also decent.
Then there's Holy Spirit Catholic in Duncanville. Maybe they're full.
Bishop Dunne is Catholic and in the South Dallas area, but I think it's my least favorite.
None of this is probably new information to you, but I thought I would offer it just in case.
K.