I am so overwhelmed I don't know where to start....I just want to give up.

I have reconnected with an old BF=boyfriend from 16 yrs ago this past Sept and moved in with him this past Jan. He has 2 daughters 13 & 11 from is marriage. He has been divorced for 8 yrs...It was a messy divorce and the past few years I understand that my BF worked to reconcile with BM but this nothing ever came of it. I believe the combination of this as well of the circumstances of the divoce has left the girls pretty broken. The emotional health of the girls was not clear to me right away but have become pretty glaring. Collectively the girls are manipulative, dishonest (lies & stealing), coniving and in general unstable. My BF & the BM I could write a novel on what they have done and continue to do that all contribute to this but it's pretty obvious that the girls learned these negative tratis from them both. Things started off my some makeup being taken from my bag...this was never addressed by either one of us..Me thinking it was not my place and BF felt ashamed and embarrased and by addressing it would bring to light truths about his kids I am sure she already knew. The girls have used the tactic with their BMs BF that he yelled at them and got a certain defensive response from BD so they used that tactic on me when a negative action was addressed by me when we were 3 together. Things then seemed to be stable and good untill the SD13 got suspended from school for bullying...couple wks later (wkend I moved in) she had a 19 yr man in the BMs home when she was not there...suspended again for firecrackers....then pulled in office for cyber bullying but school discovered mention of "cutting" so school officials were called in which lead to suicide thoughts and a trip for pych eval. BM has still not arranged the therapy that school & hospital had STRONGLY RECCOMMENDED.
THIS IS ALL IN ABOUT 60 DAYS. BM is single and has left them alone in the house when she goes out...brought men home for head banging sex when the girls were home which lead to phone calls to both of us getting texts from the girls asking us to come get them. The apex in this situation is that SD13 said some horrible things about BM to BD but when she got home she told BM that we said those things. My point to BF is that I will not be left alone with her nor have any type of conversation with her without him there. I told him I am not comfortable with him leaving her with me when he is not there. He knows I am being fair in asking this but will not allow a dissucssion with SD and us about the situation. Needless to say it's uncomfortable for everyone when she is here because I am PISSED, shut down and over it with her. She has lied to me, about me & stolen from me when I have not nothing but support & love her when she hated BM. My BF is so overwhelmed that he is just sticking his head in the dirt...If BM & BD are both in denial about SD13 behaviour...got another call from school about complaints of bullying so they are taking her out of the school because she is now the victim. yeah right...Things between BM and I are now icy when in the beginning was good...I was/am very guarded with her and with good reason. It does need to be said I have a better relationship at this point with SD11 but it's like I am holding my breath as she can be easily influenced that I am bad. SD11 is no angel...she is sneaking plays a mean game of 2 ends to the middle and is not on good terms with the concept of truth. I am living on pins and needles. I've been out of work for 2 years and used the rest of my assests to move in with BF. Leaving is not an option unless I win lottery but I desperately want to get this ship back on track but I don't know how.....I would settle for knowing how to cope. I have no friends of my own in my new home town and I know my BF feels very torn with me shoving the truth about his daughter down his throat and I fear it will cost us the relationship. Any advice or suggestions of ANYTHING I would be eternally gratefull.