Children can be very stressful with the news of break up; therefore you should plan with your partner how would you tell them about the news. In many cases, couples try to ignore the disagreements they have and live together for their children but if you are unable to do that, it is better that you part ways.
You should decide with your partner in advance regarding the responsibilities of your kid. Do not forget to decide the timings of meetings and spending vacations with the kid.
You must inform your child and explain to him that there will be no affect on your affiliation with him. He might ask several questions from both of you, do not stop him and let him ask anything he wants.
You should come to an agreement with your spouse regarding the expenditures of your kid. Do not forget to plan about his schooling and involve him in sports.
If necessary, you can take advice of a counsellor.
Make your kids understand that it is not the worst thing in fact; it is for the betterment of all of you. Tell him that both of you might be seeing other people after a short time.
Explain to your child that he can reach whenever he wants, you will always be there for him.