I'm sorry to hear about your situation.
Before commenting, I have a recommendation for you. If your wife is trying to take advantage of the situation, do not go to Pakistan with your kids. Leave your children with a caregiver if you go to see her to discuss your relationship. If your wife wants to see the children, offer to pay for her ticket to return. The reason I say this is that your wife/in-laws could potentially try to keep the children in Pakistan to force your hand and complicate child custody/access issues. I would also seek the advice of a lawyer so that your actions are documented for the record. In the event custody becomes an issue, you can bring up your wife's abandonment of the children.
As to your actual issue, I think you owe to to your children to make a sincere effort to understand why your wife acted as she did and see if it is possible to salvage your relationship. You need to look at all of the circumstances that led to where you are - did you have any warning that she was going to leave?
Answer the following questions for yourself: How did you treat your wife? How did your parents/family treat her? Is she a good mother? Has she been a good wife and companion to you? If you look at the situation objectively, it's possible that your wife may have some legitimate grievances that you can make better.
But, if she and her family have self-serving reasons for their actions - which you can assess better - you have to decide - is uprooting your children and shifting to Pakistan in your children's best interest/your best interest (consider their education and future)? What assurances do you have that your wife and in-laws will "sitkay dil se" accept a reconciliation? Can you be happy with yourself if you give in to your wife or will you resent her and ultimately end up where you are now? Do you/can you still love and trust your wife (or make an effort to)?
Based on your answers to these and other questions you have some important decisions to make. Good luck and iA, things will work out for the best - have faith in Allah