ROOMATE TROUBLES!!?

My bf and i live in an apartment with our roomate and her kid. Before we became roomates we were coworkers and friends. Now i know the saying "you dont know who a person is until you live with them" but i need opinions. Before we moved in together my bf and i were having issues where we were staying at and our roomate was having her own problems which made her want to move into her own place. So my bf, her and i came to an agreement to get our own place together. We did it was cool for a few months and than it started going downhill. She wouldnt come home for days and show up maybe once a week to sleep at home..would rarely buy food for the house,cook,clean, if the house was having plumbing issues or anything like that my bf and i would be the ones to tell the manager she would never do anything for the house. Now shes never home. Shell come home once a month, Pick up clothes and leave. Weve heard from friends that she got engaged and is looking for a place to live with her bf and is gonna move out of our apartment. Which is fine but she never told us she was moving or even thinking about moving. But today we saw her taking all her clothes and putting them in her car. We have a year lease and its not up until October.. I feel shes being super shady shes immature and irresponsible..i just need to vent..what would you do if you were in this situation?