Is it permissible to marry when there is a habit of anal intercourse with the wife, and is it possible to get rid of this obsession?

What you did with this woman is a grave abomination and a cause for expulsion from Allah's mercy. You have done well by feeling remorse, so make it a sincere repentance that fulfills its conditions. This act is a great sin, but it does not render its perpetrator an unbeliever. The disbelief mentioned in the hadith, "Whoever has intercourse with a menstruating woman, or with a woman in her anus, or with a soothsayer, has disbelieved in what was revealed to Muhammad, peace and blessings of Allah be upon him," is for emphasis and severity, not for exiting the fold of Islam. Your heart's attachment to this act is the ill-omen of this disobedience. Perhaps what has been mentioned about the ugliness of this act will help you abandon it, in addition to sincerity with Allah and turning to Him with devotion. Do not let waswas (whispers) prevent you from proceeding with marriage; so, go ahead and marry, and fear Allah.