Need to vent! Very long. Mother in law (bf's mom) issues

Sorry i don't know where to put this. First of most I love her, my boyfriend and I have been together 7 years we have a almost 5 year old daughter and a baby boy on the way due Oct. Things has kind of gone downhill since his mom lost her job about almost 2 years now, she worked as a phlebotomist for over 10 years and it really affected her, she just turned 54 and has some health problems but not major where she cant do anything, shes capable to work and be active to keep a lifestyle. After shortly after that she had her car repo and that just literally made her life just more miserable. She lived with her sister and brother in law as so she had lost her job she turned to unemployment for at least a year and a half and her son and I felt she really gave up her life and was just relying on that for her to just stay home doing nothing. I do know this cause she end up kicked out of her sister's and was moving in along with us who we stayed with a family member trying to fix our debt we had in a past to get a place for our family. So we moved 4 hrs away from our friends and family, she came along with us, but never have we thought she would come and not look for a job as she promises us she would. As days goes by and months gone by, she hasnt yet found a job or took initiative to do so, as I tried to help to find a job that was hiring shes always has excuses for she cant do that kind of job, or she dont want to work weekends. As for my bf and I things have gotten to points where it's getting between us, he is her only son and I see somewhat she wants her son to take care of her. She has no partner and hasnt for along time, she been dependent on her family members and now it came down to us. And her son struggle doing it all with his mom hes stresses out to drinking, he has said this and it sucks like to hear " I feel as my mom had me to take care of her when shes always been capable to do so and me having my own family to take care of its alot for one man to do so". Hes 32 and we really want our life to move forward and be family in our own space for the time being until we can get a house and we had told her this already, we are here for you when you get old and need our help and once we get a house she would move in with us, so now a year living with a family member she had to move elsewhere cause there was so many people living with her, at this time my bf mom lost her unemployment, since she never had looked for a job, so shes jobless at this time. So a family member who is a single mother, has rented an apartment of 3 bedroom where my bf obviously took the master bedroom with the bathroom leaving her with the smaller bedroom, the family member has been just so kind and just doenst have the guts to say anything about it so she let's her have it. It didnt bother us really since she didnt care but who knows sincw she dowsnt say it. Anyways we stayed here and there to save up to hoping to get an apartment. So move forward to a month ago we paid off our debt that got us to our apartment now and I could say it's been the best thing for mine and my bf relationship. Since we moved his mom just having an attitude when she first came over with a family member to help move our stuff in and not once said congrats to us but only comment she said was when my bf was putting up our shower curtain up that we got from walmart as we just trying to budget she goes" you for plastic?" And her son had came to me and told me that he was pretty upset how she acted. The whole time when she knew was trying to move out to get our own place for our family she was never supportive, and I can tell you living with her has been alot of tensions and alot of issues where she would as for money for her habits that wasn't good for health she has diabetes and her habits were to get a large cappuccino everyday but since she lost her unemployment and is jobless she knew she had to sacrifice that a little less than her usual. So she stayed back living with a family member who we moved in with in the beginning, we live like 15 mins away from them and last night we went over to have dinner since last weekend they came over for dinner with us. Anyways she was bring up how shes having a surgery and will have to stay with us for a week. And then mentioned family member lease will be up but not for another 4 months and dropping hints she doesnt know if she will sign another lease with having her there again. And she doesnt know where to go. And forgot to mention the family member been dating and seeing someone have years of being single, shes a hard working mother and with all of us being under her household and having to care for my bfs mother who is carless and jobless she takes her where she wants to go. And so she doesnt stay home as often while her son is with his dad, and I can tell shes getting to the point shes done with it all. Shes getting serious and had mentioned to me her bf has talked about moving in together. So that leave me stressing out at 20 weeks pregnant, as to the fact we just moved into our very own space without the stress and tensions and now all i can think what if she tries to come stay with us now after knowing we wanted space and to rise our kids just us for a couple years until we take her in with us when buy a house.