What is the ruling of Islamic law regarding the cessation of marital relations and the husband's squandering of his wife's rights, due to his inability to consummate the relationship except by using his hand for arousal, and his refusal to admit that this is a result of masturbation?

Masturbation is an ugly and reprehensible habit. If the husband stimulates himself with his hand, this is impermissible. However, if he uses his hands on a part of his wife's body, there is no harm in it, as long as it does not result in any damage to you. You are not obligated to accept what is impermissible. If he abandons you without a legitimate Shar'i reason, he is not permitted to do so, and the wife has the right to conjugal relations according to what is good and reasonable. It is advisable to pray for him and advise him gently. If he does not respond and you see your best interest in separation, you have the right to request a divorce or khul'.