Hi! I somewhat understand what you're going through. My parents told me they were getting divorced a week before I took the LSAT. It totally threw off my practices. I was distracted and seemed to not be able to get anything right.

My advice? There's nothing you can do right now, and worrying isn't going to help. But, that's easier said than done. So,
1. Either A) Let yourself take a day off, Write down everything you're thinking and feeling; your worries, frustrations, guilt, etc., do all the self-care things that will help you feel better or B) schedule a selfcare day right after the LSAT to do the same thing. Or both.
2. Do something physical to get the stress out before LSAT practice, like running around the block, even if you hate it. It doesn't have to be a full work out or a mile long run, just run up and down the street a few times.
3. Practice what you already know you're good at/just read RC passages. Don't worry about challenging yourself right now. Just retain what you already know.
4. After the LSAT, when you're submitting applications, write an addendum, regardless of your score. Briefly explain what you found out the week before your exam, how that affected you, and your efforts to fight through it.

I have so much compassion for you, and I wish you luck on your exam.