My question involves landlord-tenant law in the State of: Mississippi

So last year was a round year for my family. My mother became unemployed and we closed my family's company. Being a college student with no car and taking 21 hours, I don't have immediate access to a place of employment. Well long story short, I moved out of my old apartment into a house with two other roommates, a buddy of mine I went to school with and his girlfriend.

Well all was great for the first few months, but now they are treating me like shit because of several events that were blown out of proportion. Now the girl owns the house, but I never signed a lease of any kind, nor was I asked to. The original plan was that we'd pay for bills we used three ways equally and split the cost for groceries we used. Well they buy a lot of expensive food and I don't, but they always charged me for it even if I didn't use it. Now they have rented the extra room we have to another guy we know without asking me, which is fine because she does own the house, and they have a dog now, again with out my knowledge.

Each day they increasingly take cheap shots at me verbally and are just wearing me down mentally. So long story short, I was wonder if I have to give them 30 days notice that I'm leaving and be fine without having to pay anything. (Although I was planning on leaving enough money to cover my share of the utilities for the time that I'm there because I am still using power, water, etc.) I can't stand living in a house that I'm constantly being ganged up on.

Some other facts are that now that there are four of us for some reason I'm still paying the same amount of rent as if there were only three of us. I don't know how their math works, but they've told me that's the rules so whatever.

Also, the two guys and several of their friends are constantly smoking week in the house, which I don't do AT ALL, and have recently started snorting coke, at least I think it's coke, so I'd like to get out before we have a raid on the house. I think Mississippi law states that if drugs are found in "public" areas of the house then everyone is liable, but I don't know where they hide their stuff so I'm always scared about that.

Please, any info would be greatly appreciated.