my step dad and my mum smoking marijuana, and are they alcoholics?

okay, well basically we moved into my new house around three years ago, we became close with our neighbours who were like family to us. It was a woman her brother her daughter and son and her ex partner living their. Her brother was a bit of 'loud mouth kinda guy'. He used to help my mum who was a single mother of three for a few weeks, then i was seeing him more and more often around the house and having dinner and so on. Finally my mum and him declared that they were dating. I was happy for them, my mum had been single for a long time. Everything was going amazing, my once over weight mum lost three stone and she put it down to 'being in love'. However i knew from various people that my mums boyfriend had, had his fair few problems with some hard drugs and petty drungs, and also alcohol. I knew that he hadnt touched a drink since him and my mum met. My mum used to drink a few glasses of wine a night, but recently shes been having arout 2 bottles which is so far over the recomended amout. Her boyfriend has a couple of cans which is usual for a man, however he shouldnt be because he has had previous problems with alcohol. A few months ago it was his party, loads of people were over getting drunk and dancing and singing in the garden, when his neicec told me she'd had some dope, fair enough, she'd got it from one of his mates who he'd had some off already. This was the first time, the second time was when i walked down stairs late at night to find him ripping a ciggerette into bits, i played dumb and asked why, he said, if i roll them again they go further, i could smell the dope, im not stupid. Then last night i walked into the house and saw my mum sitting in the corner, almost statue like but shivvering, i'd been star gazing with his neice who lives opposite i didnt think they'd still be awake. Mums eyes looked bloodshot but i thought it was just because it was early in the morning around one ish. But then when i got into bed i realized i hadnt got my duvet which i'd left down stairs so off i went to get it to smell weed, it was sooo strong it was unbelievable. They must have been doing alot of it, i asked where and why he had it and he said 'oh a mate gave it to me to try' i was furious. I know this is going to lead onto other drugs because he has been an addict. Their planning on getting married next year and having another baby, i know my mum will be left struggling to keep the family going when he suddenly leaves because of a stupid reason. They always argue and i always used to be a mummys girl, she loved me sooo much we used to go out for meals and she would treat me to arty things that i liked and she used to put them under my pillow, stupid and childish maybe, but it was our thing, now all i get is, **** off you fat ****. Thats what she said earlier when my brother had a strop because there was onion on the pizza he'd just brought, which made him have a strop because he'd spent thirty pounds on it, then he made me feel bad so i gave him the money for it, thats all i have till the end of the month. I can only see this going badly, i dont know what to do about it, help please? thanxs Emilia, 15