What should i do to get my girl freind to pay her share of the bills?

I live with my girlfriend and her two children from her husband for 12 years now ,we have two children together i have asked her to pay her share of the bills she refuses to pay any of the bills she also has her 18 year old daughter living her and i asked her to pay rent she will not i have aked her to leave many times she will not leave ,i dont want to leave because i love my two children 5 and 10 year old girls,So i continue to strugle meeting all the bills every month on my own ,rent electric ,gas ,phone ,intrenet ,insurance's ,car payment .The only thing she helps with is some of the grociers and cooking and some time puts gas in the car.
Signed no help in buffalo