The mother has right to nourish her children in case of daughter up to the age of 9 and the son up to the age of 7. If the mother of the children (your divorced wife) marries a person who is not a relative of your children then the right of nourishment shall go to their nani. All the affairs related to the children are noteworthy; hence it shall be far better not to give talaq to your wife though you have to face some problems, rather invite 2-2 persons from each side who are educated, religious, sympathiser and influential. They should hear the matter of both of you and come out with some solution and settlement. In case of talaq, most probably there more problems shall creep in. Yet, if you have to divorce her then give only one talaq. Also clear all the matters before the talaq so that no dispute happens later.
Allah knows Best!
Darul Uloom Deoband