All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
The parents have a great responsibility towards their children, among which is to take care of them in their religious matters as well as their worldly matters. So, they should nurture them on the principles of Islam and good morals; the evidence for this is the saying of Allaah (which means): {O you who have believed, protect yourselves and your families from a Fire whose fuel is people and stones.}[Quran 66:6] Moreover, the Prophet said: “Every one of you is a guardian and is responsible for the people under his guardianship; a father is a guardian and is responsible for the people under his guardianship.” [Al-Bukhari and Muslim]
Also, the parents should be keen to be just between their children in everything including affectionate matters. In a Hadeeth, the Prophet told Basheer, the father of An-Nu’maan, may Allaah be please with them both, when he wanted to call the Prophet as witness to giving a donation to An-Nu’maan without giving the same to his other children: “Would you be happy that they will all be equally kind and dutiful to you?” He said: “Yes.” Then, the Prophet said: “Then, no (i.e. call me not a witness to this).”
Ibn Qudaamah said: “Ibraheem (An-Nakha’i) said: “They liked to be just to them (their children) even in regard to kissing them.”
Indeed, favoring some children over others may lead the children to be undutiful to their parents; so the parents should be aware of this.
On the other hand, the children should know that the negligence of the parents (in their regard) is not a sound reason for them to be negligent about the rights of their parents; rather, they should be kind and dutiful to them in any case.
In fact, you did well by helping your father financially, and you should continue to be kind and dutiful to him with all possible means of kindness.
Besides, you should not forget to earnestly supplicate Allaah to rectify your parents and make them affectionate and kind to you. Truly, the hearts of the people are in the hands of Allaah and He turns them as He wishes. For more benefit, please refer to Fataawa 84942 and 87019.
Allaah Knows best.