Is the husband sinful if he continues in a marriage where he does not feel love towards his wife, and only comes to her rarely, knowing that she is hurt by that, and he has committed adultery and masturbation to satisfy his urges?

You should not divorce your wife, especially since you have children with her and she is content to live with you, in order to avoid scattering the family and losing the children. You can marry another woman while keeping your first wife. Remember the words of Allah Almighty: "And live with them in kindness. For if you dislike them - perhaps you dislike a thing and Allah makes therein much good." (An-Nisa 4:19) And the saying of the Prophet, peace be upon him: "A believing man should not hate a believing woman; if he dislikes one of her characteristics, he will be pleased with another," or he said, "a different one." This woman might be better for you than others.