No one claimed she is mother of the year but your ex definitely isn’t dad of the year.
I have actually been through an incredibly nasty divorce. Fucker wouldn’t move out either. Thought I was going to do serious time in order to be rid of him, and at one point thought it might be worth it.
I’ve also been through several custody battles - although not my own kids, I’ve been present in the courtroom as a support (which I think I might need to tell you isn’t something that’s a usual occurrence, you can’t just sit in, you have to get the judge’s permission so should give you an idea of the sort of cases I was in) as well as helping work on statements, supporting through things like section 7 reports, section 37 reports. Really nasty custody battles. Some serious shit. DV. International law. My nearest and dearest have some really shitty exes. So no, don’t presume anything.
I’ve also been the kid. I was a ward of court because I also have 2 useless parents.
Fuck me though. 2 things come across in your posts - both you and your ex are very selfish. He has a child. He has parental responsibility. This will have an impact on his life. His finances. His work. That’s what happens when you have a child. Medicines etc - he should have these at his house already. He should know the routines. He can get an emergency prescription by calling 111. This is basic parent stuff.
Your naivety is the second thing.
You were dating his dad for 5 minutes and you don’t even live together. It’s fine not to want an unexpected resident step child, but you knew he had a kid. You don’t seem to have a good understanding of what sort of commitment this is. You are responsible all the time for your child - even if you only see them for a night or so every 2 weeks. You claim he’s a good dad except you’ve not really seen anything that demonstrates that and the stuff you’ve posted suggests he isn’t a good dad. Your ex doesn’t even give up his room for the measly nights he has him. Bet the poor kid is on the sofa now, waiting for everyone to leave the living room so he can finally go to sleep. Great parenting.
Obviously you’ve broken up now (which is for the best). Move on and be grateful that you are all able to.