Do I have to include my "step-father" on my FAFSA?

I’m in a very unique situation when it comes to my FAFSA, I’ve tried to search for someone with a similar situation with no luck.
So my mom married my sisters dad years ago, before I was born. They were poor at the time and decided to separate because they could not afford a divorce. My mom went on to date my dad and I came along, but my parents separated about 7 years ago and I now live with my mom. I mostly support myself financially, with some help from my mom.
So my question is who do I include on my FAFSA? Of course my mom, but do I have to include my moms husband who she is separated from? Because if I do I have no access to him or his tax information, my mom hasn’t spoken to him in years since my sister turned 18. My father doesn’t support me in any way either, so how do I go about this?

Are your oarents legally separated? Do,they maintain separate residences? Do you live with ONLY your mom at your home?

If so…you list only your mom on your FAFSA.

Now…if you apply to a school using the Profile, thats another story.

I hope others can confirm this, but I think you just have to put your mom’s income down, since she is separated.

And yours unless your mom’s income and other criteria would qualify for auto zero EFC.

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but my parents separated about 7 years ago and I now live with my mom
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From these words, it sounds like the ONLY parent you’re living with is your mom (not your dad, and not her “legal” husband). Is that correct? If so, then just your mom’s info goes on FAFSA.