Alright ladies, I need Kansas custody advice regarding infants.

My son is five months old and I provide all care for him. His father and I were never married and were only together for one month after the birth of my son. His father has provided absolutely nothing for him and only seen him a handful of times for a few hours and only if I bring my son to him, he has never gone out of his way to get a ride here to see him even with me offering to give him a ride back to his home after visiting. He refuses to allow me full custody and does not stick to his word or a parenting plan. I have also learned he is now on meth and other substances and he has admitted to not being sober and I do not want him anywhere near my son. What do I do?