So, trigger warning before I say anything else (TW. substance abuse and self harm)

Okay, so I'm an 18 year old girl from australia and I suffer from BPD. I live with my girlfriend and her dad who is away half the time because he is a miner. This is good because then I get to spend a lot of time with my girlfriend, only problem is her sister abuses drugs and alcohol all the time around us and is an absolute bitch sometimes. This causes a lot of anxiety for my girlfriend and among that I also have extreme outbursts that push her away a lot of the time and I feel horrible for it. Now, right now I just feel like I need to vent because I'm in the middle of a sort of episode and can't fully escape it because I said a lot of hurtful things to her because it's my grandma's birthday and she said she would come with me, only problem is she's going to turn up high as fuck because she went to her friends place. I was supposed to go too but I started feeling empty and emotionless inside because I didn't want to be high at my grans birthday but at the same time I have a real problem with weed and am trying to quit it, going to her friends place often ends in late night walks home stoned to the bone. It's fun but I feel like I'm ruining my life by avoiding my friends and family by smoking and pushing them away because I'm ashamed of it and I lie about it and my BPD causese to be so stressed and mentally ill that I become suicidal and often want to cut myself just so I feel something and I'm not in this state where I can't feel any emotion. Another thing is I am hypersexual sometimes and it gets in the way because my girlfriends libido is so low and it frustrates me, It sounds emo but honestly I just want my life back on track and my girlfriend makes no attempt to help me because she becomes frustrated with me because I can't help but come off as offensive toward her sometimes because I take it out on her. Anyway, I really just want someone to talk to about it all, I have no one  except my mum but she is going through a lot as it is and just want someone to be able to understand. 

Im sorry if this is in the wrong community I just feel all over the place. Thankyou to anyone who reads this.