Do your parents consider themselves separated (maritally) or is your father just working in a different place? They don’t have to be legally divorced or separated to qualify for filing FAFSA separately. If they are separated, and you live with your mother, she would file the parent’s part of FAFSA with her income, including spousal support and child support). Even if they still file taxes jointly, you can file with a single parent but you have to sort out all the income separately.
If your parents are still married and just have two households because of a job, then FAFSA is filed as married. With a family income of $80k, you likely will not qualify for federal aid like a Pell grant, but you might still qualify for need based aid from schools.