Praise be to Allah.
It is part of Allah’s decree for His universe that He has made this world the realm of troubles and problems, sickness and separation, exhaustion and tiredness, as trials for His slaves, to see whether they will be patient or impatient, and so that they will long for the Hereafter, Paradise and that which is with Allah, where there will be no toil, distress, exhaustion, hardship, grief, death, sickness or separation. This is Allah’s decree for His universe, and the way of Allah cannot be changed.
In your words, is the answer and remedy for what you are faced with. Your relationship has come to an end with separation and divorce, and you do not intend to take her back. She is sick, suffering from a mental illness with which it is impossible to establish a normal marital relationship. What appears to be the case is that you tried but you did not succeed, so what comes next? Why hold onto a rope that has already been cut off? Why live in the shadow of wishful thinking and impossibilities?
You gave a clear answer to these questions, and we appreciate your openness: “my heart wants to take her back but my head says no.” This is the entire story and the entire solution. The heart is inclined, but reason corrects you and prevents you from stepping onto that slippery slope.
But you have to give precedence to strengthening the resolve of your mind, so that you can forget about her completely. That may take some time, but in the end it will come, according to your strength, resolve and certain faith that Allah will compensate you with something better than her and will compensate you for the calamity with something better and will reward you for what you have suffered.
Ibn al-Qayyim (may Allah have mercy on him) said:
If there is no way for the lover to reach his beloved, either because it is not divinely decreed for him, or because of some shar‘i impediment, or both, then this is an insurmountable problem. Part of the remedy is to make himself lose hope and despair (of ever reaching his beloved), because when one loses hope in something, he will be relieved of worrying about it and will stop paying attention to it.
If the sickness of love continues even though he has given up hope, then this is a sign that he has developed some serious psychological problems. In that case he should move on to another remedy, which is to address his mind and think rationally, because it is known that being emotionally attached to that which one has no hope of attaining is a kind of insanity; the one who is afflicted with that is like one who falls in love with the sun and thinks constantly of climbing up to it and running in its orbit with it. Such a person is regarded as insane by all rational people.End quote from Zad al-Ma‘ad, 4/251
You are still young, as you stated in the details you gave (that you are thirty-four years old). It is not fair, it makes no sense and it is not wise to spend your life regretting what you missed or something that cannot possibly come back under any circumstances. Look for another wife who is suitable for you, and start a new page in your life. Life does not stop because of separation or failure, and nothing could make you forget a woman except another woman who is more suitable for you.
Ask Allah for guidance (istikharah) and look for a wife who will bring you happiness, and cut off all ties with your ex-wife, once and for all, because she is no longer permissible for you now, as you are divorced, and there is no point in keeping in touch with one another on the phone. If you can change your phone number, then do so, so as to stop her calling you and causing you distress.
It should be noted that forgetting may take some time; as we said, that depends on your strength and determination. Ask the Controller of the hearts to remove from your heart whatever is left of this relationship and ask Him, may He be glorified, to reward you for your calamity and to compensate you with someone better than her.
We ask Allah to grant you peace of mind, a bright future, and a righteous wife who will compensate you for what you have missed, and that Allah will grant you the reward of those who are patient.
And Allah knows best.