Hi Missy, you said it all in the title of your post. You are going through a lot right now and have an unbelievable amount of pressure on you. Your boyfriend is not there to support you and his presence IS making your life worse.
I imagine you swimming: then you have all of these weights tied to your body, one by one you are allowing them to drag you down until what? YOU go under. You need a life vest not more crap.
It's nice to be depended on but not ok to be dumped on. I really don't like that your boyfriend is verbally abusive either. That just really infuriated me.
Rose had a lot of good points. One being how you view your problems. One big pool of quicksand or small pieces of gum on your shoe that you remove one by one. I went to a weekend therapy thing and when it was my turn the T had me take pillows from a giant pile and place them on the floor representing each of my anxieties/problems. Big and small. When I could visualize them that way it felt so much more accesible.
Do you have a good friend who can be there with you to go through this process so you don't have to face it alone? I wouldn't worry about it being too cold for your boyfriend either. Seriously? if he wants to be warm then he can take himself and his crack habit somewhere.
Try to imagine yourself in the best situation possible. Is there a time in your past that made you feel good about your life and yourself? Are there steps you can take to get yourself on track again?
And please don't take on your sister as well. We all make decisions with our own free will.
It is not humanly possible for you to have all of these people hitching a ride on you!