Can you even believe this?

I met the father of my son when I was 15 and my son was born right before I turned 19. My ex had a good job and I stayed home with my son. My mom was constantly interfering with how I raised him and she started keeping him on the weekends but then she started wanting to keep him more and more at night until it became every night and she would tell me that I was just his babysitter and I should only have him while she was at work. Right before my son turned 2 I found out my ex was seeing someone else and told me to leave his house and take my kid with me. I had no job or work history so I tried for months to get a job but couldn't. Then I met chris he loved my son and treated us good. When I decided to move in with him my mom filed a petition to get emergency custody of my son. I guess because we were planning on moving to another state. She lied and said that I would leave for months without checking on him and I only wanted him when she didn't give me my way. Cps believed it all they told me that chris wasn't his dad so he might be abusive towards him and that I didn't have a job and chriss job didn't count because he wasn't daniels real dad. My mom told them I was addicted to xanax because I was given lexapro for anxiety and xanax temporarily while the lexapro built in my system I gave them permission to get my medical records and took two drug tests for them. In court they still said that I was taking xanax without a prescription and they told me that if I tried to fight it the state would get my son. They told me to give joint custody of my son to my mom and make her the primary custodian and when I was working I would get full custody again. But now my mom won't answer my phone calls. She knows I don't have a car because I had a wreck and I had to walk 4 hours to her house because she didn't care about letting me see him. I have a job now I live in a good neighborhood but she still won't give me my son. How can I get him back and y did cps treat me this way