He hasn’t. It’s an excuse. There will always be an excuse.
I think ‘abuse’ is a loaded word and in situations like yours, an unhelpful one. It feels ‘too big’ for the situation, then you think ‘he’s not abusive’ and it makes you think ‘it’s not THAT bad’.
Just think of it as awful or nasty behaviour. Don’t try to work out where it fits on the ‘abuse’ scale.
It really doesn’t matter that this specific thing was ‘once’ (or more likely once SO FAR), look at how he has been since DS was born until he started shouting at you. Is THAT how you want to live for the next 60 years?!
You’re not skint, you’ve got savings, yet he’s asking you if you needed to buy a coat. Not a diamond tiara, a coat 
I didn’t want to bring this up (yet) because I know what you’re going to say, but you need to consider that he may have an OW. He’s showing several signs of it being a possibility and explains the worry about money, ‘long hours’, out a lot with ‘friends, suddenly having to ‘work’ not trusting you etc. I don’t think it needs to be your main focus, though I’m sure if you found one you’d (rightly) tell him to stay at his mother’s, because whether he has or not, there’s already plenty to think about whether you want him back or not.
Give him their phone numbers, let him decide whether to apologise to your friends or not, but if he does then offer no more thank acknowledgement he’s spoken. No great or thanks or anything. He’s looking for ‘brownie points’ don’t give them.
Look, I’ve been there where they’re treating you badly, but you love and want it to be ok. Other people dissing them just makes you upset or angry and because you love them, you defend them. It’s natural, but ultimately unhelpful.
As I said earlier, I think he’s actually now shown you who he is, since DS’s birth and I think he will get worse, not better.
I fear you’re going to let him come back home 😔 but my biggest worry for you is that you become the frog in the pot.