Hi there Kimberly & Welcome to 3FC =)
Eating better isn't just good for those of us who need to lose weight. You can include both your husband and son in your efforts without them even really knowing or needing to change much.
Cooking healthier meals...keeping healthier snack choices on hand...they can maintain on their own and you can watch the serving sizes for yourself!
You can definitely do this.
Best of success!