Roomate troubles i don't know what to do...?

ok so here's the deal in march me and my used to be best friend moved into a house together with her 3 year old son... he's not the problem... it's the fact that she is now dating her baby's daddy... the guy is a low life with 3 kids in total and my roomie's son is the middle kid... they are both on welfare tho my roomie works part time cleaning hotel rooms... she got into a fight with our friend rach and then slowly stopped talking to me... the fight was mainly about stolen rent money. last month we had our rent money out on the island in the kitchen in an envalope... i had a cheque she had cash... we weren't sure when the landlord was coming to get it... anyway the envalope went missing... she blamed rach because her car was broke and shortly after went back on the road. i know for a fact that that's not where our friend got the money. my roomie's bf is in jail on weekends and his family was always in and out of our house... money was slowly going missing as soon as her bf showed up. anyway now the bf and his 6 year old are living at the house... they come home at 10;30-11 at night and either leave before me or stay in bed till i leave... so i dont see them much... i guess when the rent money went missing the bf forked over the money for her to pay rent... which was about 20 days late... he collects welfare and has his sister her bf and their kid living in his appt and they collect welfare and pay him... so all of them are collecting welfare for rent and my roomie isn't paying the bills... which are all in my name. i dont see ehr so i can't confront her... she dont have a cellphone so i cant call her... she wasnt like this before the bf came into the picture but she just changed. which sucks... now the normal thing to do would be to tak to the landlord... however he is my boss... and i vouged for her when we decided to rent because back then she was reliable... it's the bf that's changed her... anyway i dont want him to know the full extent of everything the bf is bad news... with cops and drugs and theft in his past... and present... i just dont know waht to do... i thought of contacting welfare and reporting that they are all getting rent money (4 adults) and only 2 places are being rented... but will they look into it? any other ideas of what i should or could do?