How can a woman act regarding her inability to perform ghusl and prayer due to the nature of her coarse hair, fearing her husband's reaction, who dislikes curly hair, especially since she suffers from a curved back, which places her in a dilemma between pleasing her Lord and pleasing her husband?

Abandoning prayer is a greater sin than adultery, theft, and drinking alcohol, by the consensus of Muslims. Neglecting ritual purity (taharah (definition)) that is obligatory for prayer, when one is able to perform it, is among the major sins. What the questioner mentioned is not an excuse that permits abandoning ghusl (definition) (ritual bath). Therefore, one must purify oneself in obedience to the Almighty's saying: "And if you are in a state of janabah (definition), then purify yourselves." Pleasing Allah is more important than pleasing people, and it is not for the husband to disparage Allah's creation. The questioner must make up the missed prayers, for Allah's debt is more deserving of being paid.