Bless you - it must be such a stressful time for you - arguing while pregnant is horrible I know (I had many rows with my then husband throughout mine unfortunately!)
There is a positive to this situation, tho it may not feel like it now. Many men his age (and any age) would have little to no interest in the baby. Some would have disappeared altogether.
To give him the benefit of the doubt, he does sound like a committed and enthusiastic (if clueless and misguided) young future dad..... Hopefully once baby is here that enthusiasm can be channeled into stuff that is ACTUALLY helpful to you and the baby, like taking them for a day for a while to give you chance to get stuff done/sleep.
Nights with a little baby can be really HARD - I don't know if this would be an option for you, but if you do find you struggle, would you even possibly consider letting your ex stay over in the spare room if you have one, maybe have the baby in with him (NOT in his bed obviously), do nappy change when needed and comfort and only bring them through to you when they are hungry - like a night nanny if that is the right name for it? (Some moms employ someone to stay over and do this occasionally or for short periods when they are struggling to cope, or unwell, or just need more sleep!)
If possible TRY to avoid arguing with him - for your own mental health and also because, it would be a marvellous thing for your baby if the two of you can somehow forge a really strong co-parenting relationship, and baby gets two absolutely committed and loving and involved parents (it can definitely be done).
But you are quite right, no overnights until you feel comfortable and baby is weaned -might be at least a year before you feel ready and he just needs to suck that up. But everything WILL change when baby is here - how you feel, how he feels - your whole worlds are going to change, so making exact plans at this stage may not be the best idea. Also as someone said up thread, BF is brilliant if you want to do it but maybe don't totally set your heart on it as sadly it does prove impossible for a small number of women; and others find it too hard, and damaging to their own mental health, so sensibly decide to stop. You are very likely to be able to manage it with good support, but it's not 100% guaranteed and I always think it's best to at least accept that on advance, and imagine the possible alternative and the fact it will be fine.