I'm sorry, it shouldn't be like this (obviously!!) As PP said, you need to leave him & the job, your own title says it all!!
look for another job, more hours at your other job & apply for all the benefits you can.
his business won't be screwed without you, he'll find a mug to bail him out, but even if is is, he only has himself to blame!!
YOU need to be strong enough not to have him at yours & not sleep with him.
Do you have a friend who could come and stay for a couple of weeks to make that easier?
I was your age when I split up with my (first) DP, I remember feeling like it was the end (and stupidly) like I was 'too old' to start again! In reality I was SO young & you are too. We both had to move out of our house as the owners (my parents neighbours I had known for YEARS) only wanted a couple!! Idiots.
so you have the advantage of not having to move at leat!!
AND you're going to have a baby soon. You & your baby can be a tight little unit.
he has NO 'right'' to be at YOUR appointmements or the birth, and I wouldn't let him be! You don't need to be doing any hysterical bonding!! Keep him away & find your feet.
he doesn't have rights, but he does have responsibilities!! Get whatever information you can to prove how much he takes out of the business. But don't count in CMS.
do not put him on the birth certificate & give YOUR baby, YOUR surname!! You choose the first name/names.
be string & you'll be fine!!! Your heart WILL mend xx