HELP!

I’m currently pregnant and I’m already aware that I’m going to be a single parent. In the beginning I thought we were going to be able to co-parent, but slowly over time my child’s father started sending different signs 1. I got pregnant in a threesome 2. It was a couple. At first they seemed okay because I told them I didn’t believe in abortion and that I was going to keep the baby. Everyone was on board with it now I don’t talk to them like I use to because of a falling out. My child’s father has reached out to me saying he misses me. Ask if I’m okay and when are we going to have sex again and I tell him no I don’t want to then he starts acting funny. He hasn’t done this once but twice already and doesn’t say anything else I just feel like he’s going to miss out all because I don’t want to have sex with him anymore he doesn’t even know I’m having a boy. The real question is would I be wrong for putting him on child support because I already told myself if he didn’t step up 30 days after my son is here that I was going to do it but I just really need some advice on how to deal with this situation.