It's a little complicated. I have one roommate who I maved in here with; she's the only one on the lease. I took the small office room as a sublet, which the landlord said was tied to her rent. He showed the open room in our 2br to a woman with a dog I'm allergic to, and let her move in despite the fact that we told her and the landlord she was not wanted. He also told this person a completely different story about the rent situation; my friend on the lease was told utilities were extra and that my rent could go into hers. The new person was told the utilites were included in her rent and that my rent would pay for them, which it doesn't. My friend has been stuck with a bill of over $1000.
The dog is a unneutered pittbull, who whines day and night and lives in a crate a foot too small. She let's people stay in the house when we're not home, and took all of my things out of the closet that my friend and I agreed was mine since I don't have one, and put a lock on my closet. She has yelled at and threatened me, and between her, her dog, and the people she brings over, we don't feel safe in our own home
Now I'm not on a lease but neither is she, and my friend is too meek to stand up to the landlord, who yelled at her so badly about her " poor housekeeping" (none of his buisness) that he made her cry. Ironically he has done none of the necessary repairs we've been demanding since we moved in 3 months ago, such as broken windows, tile, rodents, and the dead tree dropping branches as you try to come into the house. I didn't even care about that stuff at first, but the woman he let move in said she'd be moving out in 3 months and has showed no signs of doing so. She doesn't even have a job, she's on unemployment.
What can I do about our house being invaded like this?

I don't completely understand what you are asking.

If you want to leave and break the lease, make an arrangement (a buy out) with the landlord.

If there is no lease, simply move.

I don't understand the living situation - you are renting rooms in someone's house?

You have a lease (whether written or unwritten) with your friend. She has a lease with the landlord.

It may be that the landlord violated the lease by allowing someone to move in without your friend's agreement (you have no standing there). Or, your friend may have been renting only part of the property and the landlord was free to rent other parts.