Extreme Roommate Problems...

First off, I apologize if this is posted in the wrong section. 
Here's some back story to better understand the situation. In February my boyfriend & I decided to let my best friend move in with us. She was having trouble at home. Her mom isn't very nice to her & she got depressed. We figured moving to the big city we lived in versus the town with a population of 500 would be better for her. We were already in the process of getting a 2 bedroom trailer instead of living in the 1 bedroom apartment. Everything was fine & dandy when she first moved in. Up until a few weeks ago. 
We've had to buy paddle locks to keep her out of drawers around the house so she doesn't steal things out of them, replace our door knob with one that locks so she won't steal things out of our bedroom, we've had to hide food so she won't take it on us, she steals things around the house & puts them in her bedroom. She doesn't ask for anything, just takes; including some change we've put in our change jar (for a rainy day fund).
Now it's gotten worse. I just found out earlier this week that I'm pregnant. When I told her she was very monotone, even dared to ask me if I was going to have an abortion even though I've been telling her since I've known her that all I've ever wanted to be in life is a mom. She doesn't like children, she barely keeps her sanity when my young nieces (8 years & 5 years old) & nephews (4 years & 15 months old) visited. 
My boyfriend & I are at our wits end but she's told me that if she moves back to her parents' house she'll wind up killing herself eventually. We don't want to be the cause of that. Does anyone have any advice on where to go from here????