Did war God Mars throw his sons in the river Nile?

No. Mars did not.

Amulius the brother of Numitor, after killing all his brother's sons and making his only daughter a Vestal Virgin so she could not have any heirs overthrow him - Mars either raped or seduced her. When Amulius found that she had had sons, he threw Rhea Silvia into prison and threw her sons (Romulus and Remus) into the river Tiber.