I’m sorry you’re in this difficult situation. Most people who are new to the process need time to understand the rules.
The FAFSA EFC (estimated family contribution) should be renamed. It doesn’t mean that’s what families will pay and the college will pick up the balance. The purpose of the FAFSA EFC is to determine if students are eligible for the $5900/year Pell Grant. A student with a $0 FAFSA EFC should get the entire grant. The closer the EFC is to $5k, the smaller the Pell Grant. A student with an EFC of $6k would get $0 Pell. The FAFSA is mostly income driven. It uses the financial info. of the parent the student lives with most, if parents are divorced, or both if they’re married.
Some colleges use the CSS Profile form in addition to the FAFSA. It counts income, assets, and home equity, and uses the financial info. of the parents and stepparents, if there are any.
Most schools don’t have the money to give large grants to every student they accept. Some give out merit awards based on stats (GPA and SAT/ACT scores), but those generally aren’t enough to cover the cost of attendance. Some give need based aid, but if they don’t guarantee to meet need (most colleges don’t) then that often leaves a large gap too.