Children are quite resilient. They can take any change in their stride. It makes good sense for the child to be in the same house with both parents. He would love to have his father around and will look on him as a hero. When you both go abroad, your son will learn the new language and the customs, as he attends school and makes friends. There is no cause for worry.
There are long term implications for every decision. Make your decisions after thinking them through and then take life as it comes. Surely you would like to live in an intact family, with your husband and child. Don't give place to imaginary fears.