Why Buddha was not worried about his family after enlightenment? Of course, after getting enlightened, One is free from worry: now the person is in higher dimension and is always happy, as he knows how perfect everything is.

But still Buddha's family was there; I mean, wasn't his family his responsibility?

I remember when the Buddha came back to the palace and met his wife: she asked, "just tell me, if it was possible to get enlightenment in the palace."

How necessary is it to leave our families to practice, and if it is not necessary why didn't Buddha just come back? I always feel sad when I think about Siddhārtha Gautama's wife Yashodhara.

If one is enlightened, he can not hurt anyone feelings: but Buddha hurt Yashodhara's feelings?

I know I am incorrect somewhere, because after all He was enlightened, so he can not take wrong decision.
But still Buddha's family was there; I mean, wasn't his family his responsibility?


Yes.


  I remember when the Buddha came back to the palace and met his wife: she asked, "just tell me, if it was possible to get enlightenment in the palace."


You remember? 


  How necessary is it to leave our families to practice, and if it is not necessary why didn't Buddha just come back? I always feel sad when I think about Siddhārtha Gautama's wife Yashodhara.


Gautama had this urge to find out the meaning of this life and suffering, and that was his ONLY goal. He wanted to leave so he could concentrate on that. I am going to quote Chuck Palahniuk here -If you want to make an omelette, you have to break some eggs. This is the SAME with any other goal. You have to make some sacrifices.


  If one is enlightened, he can not hurt anyone feelings: but Buddha hurt Yashodhara's feelings?


Cannot hurt any feelings? That doesn't make any sense. Feelings are for the person who is at the receiving end. Not for the Buddha. Have you heard of the saying "truth is bitter"? Bitter is a feeling that we experience because of our subjective minds. 


  I know I am incorrect somewhere, because after all He was enlightened, so he can not take wrong decision.


What's your point? There is NO SUCH THING as right decision and wrong decision. It purely depends on the context of the situation. If Gautama wants the answer he is seeking, then he has to leave the family. Period. It is NOT WRONG. He did it because he was yearning for it. It cannot happen to you or me, because we don't have the guts to sacrifice and drop everything that doesn't matter and go towards our goal. If Gautama wanted to rule the world or a kingdom, he would have taken different actions. Actions are according to the goal and the situation. Don't think in terms of marriage/divorce law or morality here.  

I also want to add finally that, to go for Nirvana is definitely a selfish matter. If I want to find out what it is, it is because it is MY DESIRE to find out. Without Desire, you cannot live, breathe, feel or do anything. It is a desire to find out about life that Gautama went forth with. And whether you like it or not, it is selfish. And why not be selfish about this? Yes you will hurt some feelings, but like I said, you cannot have everything, you have to sacrifice.