Unmarried mother needs help please!

I have two children by my ex finance, never married him, he did sign the birth certificates. Ages 10 months and three year old. Mediation is coming up soon. What type of questions or things should I have in mind when going there. He smokes pot all the time, but I dont. I didnt think he smoked in front of my children, but my oldest daughter age 9 recently told me he smoked pot while driving her to fishing, and to the store. She even drew the pipe he smokes his pot out of and said it smelled bad. She is not his child. I asked why she hadnt told me this before, and she said no one asked me. I signed up for medicaid and food stamps, living with my mother in a three bedroom house, and the children are happy to be together. He filed an injunction on me, afraid I would leave the state, said I was abusive to him in the past in front of my children, which is a lie. He was the control freak. Checking the phone when he got home to see who called, or who I called. No trust was his issue. I couldnt have friends. He wont return any toys, or clothing for the children to me. Im in the medical field and need my paper work which he wont return. He would never babysit, went out on week ends alone to drink, and we did nothing as a family. How long does this process take. The injunction of no contact is in order, but I have let my three year old call her dad when she wanted. I dont talk to him though. My children have adjusted to living with me in my mothers home and are taken care of. I love my children, and I have been the one to take them to all functions, hosting play dates for them, taking them to the doctors, being and helping them when sick, teacher ABC's, teaching manner, taking them places, and so forth. I offered him every other weekend, and one night a week during the week for over night visits, and 500.00 a month child support, he said he will not agree to this for mediation. I do not work at this time, he wouldnt allow me to work when with him. I have no car. Any suggestions, please reply asap. Has anyone else been through this, how long does it take until its over. Suggestions on counseling for the children? Suggestions what I should do about phone calls with the injunctions against me. Yes, I did admit I was protecting myself from him, I have bruises with pictures and the newspaper date on them, after I was arrested for battery. he didnt admit to anything. He told my mother he stopped smoking pot. His sister in law told me he asked her to take custody of the kids if he didnt pass his drug test. She said he drank some sort of mixture to pass the test. I previously did drugs three and a half years ago, Im clean and sober! No more drugs for me, my kids are Very important to me. He also did the drugs with me at that time. Im scared. Thank you. I have discussed a few things with my oldest daughter, and Im going to get her in counseling.
Please reply.
Thank you and God Bless