Rant about my stepsons mom 😒I’m sick of her

She seriously drives me up a wall. My stepson is 3 now and I have been around since he was born. We both lived in the same state at one point and had him for 2 weeks every month. I’ve potty trained him, I weaned him from the pacifier and bottle, everything. She decided she was going to move to another state for school. We like to call her a professional student. She has spent 5 years in college and got no degrees and she actually just dropped out. We pay $600 a month for child support and all his medical, dental, and vision. I went and bought all of his clothes for this year and gave them to her when we met up for pick up and drop off. Now keep in mind our meet up place is 800 miles away and that is halfway for both of us. I have a 2 year old son and I’m 35weeks pregnant. We had him almost all of August and she wanted him back potty trained ( again ,because she won’t keep up on it, I had to do it 3 times) and she was going to put him in preschool so we wouldn’t be able to get him again until his spring break or summer. And we want to convince her to let us have him for the full summers because 1600 miles round trip every month is way too much. Well when I dropped him back off with her she texted me husband the next month asking if I would go meet her to take him for 7 days because she had a last minute trip she wanted to take. Guys, I’m 35 weeks pregnant lol. I’m not driving alone 800 miles with a 2 year old almost term to get him for 7 days and take him back. Well she was super pissed when we told her I can’t be doing that right now and she wanted to know when we can take him again. I told my husband we can’t take him until the baby is born and a couple months old because he lives in daycare when he’s with her and every time he comes here we all get super sick with the flu, respiratory infections, whatever it is, we all get it without fail. And I’m sorry I’m not having him come her as soon as she’s born for all of us to get sick and put the baby at risk . She wanted us to have joint custody of him and then she changed her mind because she wants to keep receiving all the child support and help from us that she gets. But I’m just pissed because when we told her we won’t be doing that drive every single month she got pissed. Like I want to start taking him a few months at a time or even figure out a schedule that will work for his future schooling. But there’s no way in hell I will drive 3200 miles a month to have him here for 7 days. Anyway am I in the wrong for this? She’s so mad at me and wants me to come get him as soon as the baby’s born and I just want to tell her to just let us have him full time and she can keep getting the damn child support since that’s all she cares about. We’re hoping once she gets an actual job for the first time in her life ( you heard that right, she’s never worked) since she dropped out of college she will think it’s too hard and just give him to us . Anyhow I just needed to rant because I was so mad that she wants me to drive all the way out there this pregnant with my 2 year old and 3 year old.