You went through a lot of legal hurdles to have full physical custody of your son. For the last 10 years, he's lived with you and you've done a great job with raising him. His dad has also been involved, sending child support payments and honoring the visitation schedule.
Divorce is a frustrating, often expensive experience. One of the biggest expenses is often child support and spousal support. During the initial phase of divorce, legal separation, one spouse typically files for divorce and requests a temporary custody and support order. That often means that the person who doesn't file is suddenly relegated to weekend visits with their children, while being expected to pay a substantial amount for their care and upkeep.