Why do I keep trying to talk to my mother and reason with her?

Alright, so my family TRIES to have a little meeting weekly (usually doesn't happen). The rules of this meeting are to express any good things that happened, or anything that's been bugging you. We each take turns and aren't supposed to interrupt or take calls or text or any of that shit until it's over.

So mom talks, Brian talks, then Aaron talk. It's my turn.

I tell mom yet again that I want to spend time with her, but she locks herself in her room with her sex/pot partner all day (he spent about 9 days in a row, all day, here with her, and that just stopped about 2 or 3 days ago, so he came over shorter periods of time after that). Then mom says I don't spend time with her anyways, and she goes off on how I don't pull my weight anyway. She says I don't do all my homework or go to school when I'm supposed to, and for the last few weeks I've changed that and HAVE gone and done all my work, and when I try to defend myself, guess who calls?

Her 'boyfriend'. Need I remind you, this douchebag is MARRIED, has 3 kids (one is handicapped and the other is fourteen!), and smokes pot with mom all the time.. which makes me physically ill, as they smoke IN THE HOUSE. The walls are THIN! I can hear them having sex all the way downstairs.

Anyway, he calls, and in the middle of my sentence, she answers and walks away.

Then, when she comes back, she doesn't apologize for it, so I just know to fucking quit trying to change things, and I tell her I'm done. She always just turns all my problems with her back onto me. I can't fucking tell her how I feel, cuz it's always my fault, and I'm supposed to just deal with it no matter what, and it's just NOT POSSIBLE that my life has been a living hell.

So after I sit in my room, holding tears back (I managed not to cry. Haha.), I decide to go talk to her again. I tried to calmly tell her why I feel the way I do (and she finally apologizes for interrupting me), she slowly goes from talking normally to yelling. I keep trying to tell her to stop yelling and talk to me calmly. She basically told me that no matter what she does, I bitch about it. She said I bitched about it when he used to come over less, and I told her that I didn't know then how bad it would be later, and I'd prefer that, and she keeps giving me that "PSH" shit.

I try to tell her that we should compromise (another "PSH"), and then she goes off and tells me to worry about "my own" problems. Then she pulls the 'deal with it, he's in my life, he makes ME happy' shit, and then says she's done talking to me, cuz she's 'about to start her period and it makes her bitchier'.

Why am I in the wrong here? She's fucking a married man and smoking pot all the time, and she still hasn't gotten a job. Why doesn't she ever just listen to me? What she does affects me, for god's sake. She's my only parent!

Excuse me for wanting to be with my mother.

I know things are hard for her, but what the fuck, they're not easy for me.