Sounds liek you want to cancel due to a change in your family status. Since your children will be coming to be with you, you will need a home for them. Sounds like selling your home now would not be beneficail to you and your family.
Providing you have not accepted any offers, you can cancel the listing, and there should be no issues.
Make sure and cancel in writting and explain your situation.
Best of luck to you and your family.
Kawain Payne, Realtor