It really sounds like you are going through a lot. It warms my heart to hear your concern for your child!! Many times they get lost in the adult's emotional turmoil. Have you gotten your own place? Is there a structured visitation?
A lot of the time when a relationship falls apart, the ex's family can be very supportive. However, you need to remember, they are the relatives of your ex and the allegiance will always remain with the ex. (My daughter is going to learn this one the hard way--she is staying with her ex in laws and their charity will only last so long before she becomes a liability to their relationship with their son. It hurts me, but she will listen to no one, so I am just waiting in the wings, when she needs me I will be there to pick up the pieces.)
How does your child feel and how is she/he taking this upheaval? Is your ex supportive of the child or does she act like it does not exist? Sorry for the third degree, just need more info to see if I can offer much advice. I went through a divorce years ago with my daughter's father and am trying to help my daughter stay strong with her situation.
Feel free to message me if you need to vent!! My heart goes out to you and your child.