I don’t exist to the in laws

My SO and I currently live with his parents. If anyone has read “mil steals my clothes”, yeah, that’s me. Well after her stealing my clothes and me getting them back, I now simply don’t exist unless they want me to change/put shoes my child. Which, if anyone’s wondering, the reason I say “change my child” is because play clothes are “unacceptable for going out”, according to her. They talk without including me, the leave me alone at home on my off days, taking my child out without a word as of where. I’m literally nothing to them. I want so desperately to get a full time job, but I have no one to watch my baby, I also don’t have a car. I’m constantly stuck, I only get interaction when my SO is home. Sometimes I literally call people in my phone, just so I don’t feel alone. I’m getting so sick of it. I feel like the new kid, who no one wants to talk to. Even though I’ve been living with them for a couple years now. Part of me wants to break down and cry, but the other half tells me to stay strong. I want out, but I love my SO. I doubt he would want to leave. I just want to go home and never come back. Advice, anyone?