umm I don't think they are in heaven. They don't exist yet simply. Fate has everything written, if indeed it is destiny that you will have children, then they will be born. If it is not, if you keep your firm stance on this throughout your life, then they wont exist anywhere whether heaven hell or earth.
So that sacrifice that you mentioned does not exist. It is just that you are sacrificing your desire to be a father over your fear that they may suffer during life or in afterlife, if you do become a father.
Maybe you are just taking too much responsibility over other's deed. If it is intended that a soul will come on the earth, there is nothing you or anyone can do to stop him from coming. Plus every soul is different, and they will be held responsible for the stuff they do, not their parents.