Celibate and my child father😒

I am single and have been celibate for months now. My child father knows this but, yet he messages me always about sex even today. I tell him to please quit messaging me regarding sex but he does it anyway. This morning he agreed to go in half with me to help pay for our child birthday party. Then after he turned the conversation to ^ , he hurry up and changed his mind and said he wasn't gonna help anymore. I am tired of him , I have been doing everything for our child since birth. He bought the baby 2 pairs of shoes and 3 shirts since birth and my baby is almost school age. I told him I will put him on child support but, he told me he will just quit his job. And he barely even making money there. I just want him to step up, what should I do?