Hi,
Why not expose your kids to French? It will give them an extra advantage when they enter the job market and make them well- rounded citizens. They will also learn it very easily because they are young.
What PMM said is right. Bill 101 requires children to be educated in French regardless of mother tongue, unless one or both parents were educated in English IN CANADA.
Don't look at it as a burden, but an opportunity for your kids to learn something new.