Sounds like we went through similar circumstances to each arrive where we are today. While I did get my own place where I can house my four kids, she is staying in the big, expensive family home. I too feel that the only difference for her pre-sep and post-sep is the fact that I'm no longer there to crowd her. She hasn't had to endure not having the house, family, friends, and ammenities. Basically, I think she has had a cake walk.
I pay for all the bills but she must use the income from her 'job' to cover living expenses for herself and the kids when she has them. This is the ONLY pinch she has felt in the S so far, she doesn't have a bottomless pit to spend from. It makes the financial side tough in that I have to watch what I/we spend, but it was more than worth it in terms of giving me a breather from the stress brought on by her antics. Also, I've developed something of a separate life that helps me feel better about myself and where I am going.
Sounds to me like you need to start looking out for yourself a bit more. Having a place where you could KEEP the kids would be great and would give you a boost in the PMA department. A principle of DB'ing is if something is working, keep doing it, if it isn't, change things up. Do you see any movement on her part with the current arrangement? Doesn't sound like it to me.
Have you looked into cutting expenses around the current home in order to free up enough funds to get yourself an apartment? That is what I did in order to be able to afford my townhome. It can't go on too long as things are just too tight for comfort. We agreed that they could stay in the family home until the end of the school year. So, in Jan/Feb/March we will have to make a decision about what we are going to do and be ready to put that house on the market. It's just a house...
Think about all this... you really need to set yourself up in a situation where YOU can succeed in the things you want to accomplish. She needs to feel some discomfort from her decision and she needs to be able to see you as someone who is living life, someone attractive.