Do i need a lawyer for a child custody case involving domestic abuse and drugs against dad?

we currently have shared custody, but as we spent less time together, he started hanging out with a bad crowd again (his family) all drug addicts and bad influences he didnt want us around when we were together. when dad found out i filed for full custody because he wouldnt stop smoking pot and get a job, he flipped out, threatened to kill my family, and was arrested on a domestic. hes fighting that saying they were false charges which just shows he doesnt want to see his child right now as he has a no contact order anyway. my prosecutor for the domestic told me the no contact order was on me and i could try and contact him as much as i want which i had been emailing him. through this i realized i want us to be together although i thought i was over him before. i even dropped off child support papers for him that came to this address not to cause trouble, but he still called the police on me to have something else against me. i wont be trying to contact him again, but this is a huge mess. he may bring an attorney to the custody hearing next friday and he might p a drug test by then. it will have been almost 40 days since hes probably stopped but hes always said hed only stop long enough to keep his son. and hes going to say im crazy so its like this. without an attorney that he may have, and although theres an active domestic case, can i petition the court for a hair follicle drug test and a psychological evaluation for the both of us? does he have a chance at keeping shared custody?