Will the wife be sinful or tormented on the Day of Judgment for remaining with her husband who does not pray most of the time, given that her family knows about it, and she is financially unable to seek a divorce and fears being deprived of her daughters? And to whom would the custody of the two daughters be granted in the event of a divorce?

Your husband, who is negligent in prayer, is in grave danger. You did well in advising him, and continue to supplicate for his repentance and guidance, for the guidance of one man is better than red camels. Separating from a husband who neglects the rights of Allah is commendable, but you are not obligated to seek a divorce if you see a benefit in remaining. Custody of the children is your right unless you remarry, and if a dispute arises, the Sharia (definition) court will be the arbiter. It is preferable for the spouses to agree on what is best for the children to spare them the negative effects of separation.