How to get full custody without a lawyer in NC?

My son is 7 and his bio dad & I have been divorced since he was 2. He went to his dads every weekend or at least every other weekend ever since then. Well recently, last fall, he decided to take off to Florida with his new girlfriend. He’d call our son maybe once every two weeks for only about 5 minutes on the phone… well now it’s gotten to the point that my son is acting out HORRIBLY in school and we’ve discovered it’s because he’s angry with his dad (he hasn’t seen or spoken to him since January now). I’m wondering if anyone could give me some advice on how I can obtain full custody? I asked if he wanted to sign his rights over but he doesn’t want that, for whatever reason. He doesn’t make any effort to talk to or see him and doesn’t pay his child support. Is there a way I can do this without having to pay $2000+ for a family court lawyer??? To add: I feel it would be better for him to sign his rights over because he obviously doesn’t care about him enough to even make a simple phone call to talk to him. Plus IF he were to reach out right now, he’d give him empty promises of coming to see him like he’s done before and I’d rather my son forget he exists rather than continue for him to have false hope that his dad is coming back and causing him to act out in school… I live in NC.