If you were married in a Catholic church then one of the vows you make is to welcome children into your marriage and raise them Catholic. If your DH no longer wishes to practice the faith he was raised in that is his free choice. However, you are also free to continue your practice of the faith and why should your child be denied to be part of a fundamental aspect of who you are and what you believe?
Also the idea that you just be a Catholic on your own time for an hour on Sunday and not let it be expressed in the rest of your life (i.e. saying grace before or after meals) is the antithesis of Catholicism and Christianity. If you believe, it is not a little hobby.
I appreciate that with atheists in the family you make compromises to keep the peace, but not compromise your fundamental Catholic beliefs.
For example in your dad's own home I think he gets to decide if he says grace or not. In your own home, you can say grace when your DH is not there and you can also explain to your child that saying grace can be silent and can be said interiorly.
Church teaching from the Catechism:
2221 The fecundity of conjugal love cannot be reduced solely to the procreation of children, but must extend to their moral education and their spiritual formation. The role of parents in education is of such importance that it is almost impossible to provide an adequate substitute. The right and the duty of parents to educate their children is primordial and inalienable.
2222 Parents must regard their children as children of God and respect them as human persons. Showing themselves obedient to the will of the Father in heaven, they educate their children to fulfill God's law.
2223 Parents have the first responsibility for the education of their children. They bear witness to this responsibility first by creating a home where tenderness, forgiveness, respect, fidelity and disinterested service are the rule. The home is well suited for education in the virtues. This requires an apprenticeship in self-denial, sound judgement, and self-mastery - the preconditions of all true freedom.
2226 Education in the faith by the parents should begin in the child's earliest years. This already happens when family members help one another to grow in faith by the witness of a Christian life in keeping with the Gospel. Family catechesis precedes, accompanies, and enriches other forms of instruction in the faith. Parents have the mission of teaching their children to pray and discover their vocation as children of God. The parish is the Eucharistic community and the heart of the liturgical life of Christian families; it is a privileged place for the catechesis of children and parents.
2227 Children in turn contribute to the growth in holiness of their parents. Each and everyone should be generous and tireless in forgiving one another for offenses, quarrels, injustices and neglect. Mutual affection suggests this. The charity of Christ demands it.
2228 Parents' respect and affection are expressed by the care and attention they devote to bringing up their young children and providing for their physical and spiritual needs. As the children grow up, the same respect and emotion lead parents to educate them in the right use of their reason and freedom.
This is what your DH signed up for. He may have been personally disinterested or disinclined to get involved but it is definitely not JUST to act as if it is a big surprise if a Catholic partner is raising their child Catholic.