How does court work/ co parenting

I’m terrified, long story short.

I have a 10 year old and I was co parenting with her BD, 3 years ago we rekindle and that was just horrible. I was parenting all myself, I constantly told him I felt like a single parent. He doesn’t know how to parent, the mom would take care of the kids. I left and sadly when I left I found out I was pregnant. He’s already throwing in my face how he’s getting 50/50. With our daughter our court order was Wednesdays and every other weekend. He didn’t even keep up to Wednesdays… he’s doing this to spite me. I am terrified. I’m not sure how or what this will look like..

oh I also don’t plan on giving this child his last name, seeing it first had with our daughter. I regret doing that..

any advice, I’m so scared

In the past three weeks he hasn’t going to any U/S, any blood work or doctors appointment, I am high risk and been bleeding so I’ve been seeing a lot of times already and he has not gone..