How can God forgive a man who deprived his wife of having children because he refused treatment?

It was more befitting for you to pursue the permissible means of treatment for conception, as the Messenger of Allah, peace and blessings be upon him, said: "Seek treatment, for Allah Almighty has not sent down a disease except that He has sent down a cure for it, except for one disease: old age."

Procreation is a legitimate objective, a natural desire, and a shared right of both spouses. However, refraining from treatment is not forbidden. Your wife had the right to seek divorce due to her harm from not conceiving, but since she persevered, she has done well.

You must treat her well, compensate her with your affection, help her obey Allah and be content with His decree, and occupy her free time with what benefits her. If treatment can still be pursued, that would be more appropriate.