he has noticed he's slipped back into old ways, that he's feeling good that he noticed though....but then sent another one saying "also if you noticed that things were getting bad before I did, why didn't you say outright because then I don't know things are bad again so it's also on you to call it out
So he's praising himself for noticing that he's been treating you badly, and throwing in a bit of blaming you. What a saint. By admitting that he's 'slipping back', he is admitting that his default position, the position that requires no effort for him, is the position where he abuses you.
Surely if he was abusing me though he wouldn't be apologising and admitting fault like this
Have another look at the abuse cycle. It's got the 'apology' bit on it. You are firmly and undoubtedly on the abuse cycle with him. He'll apologise to make you stay, so that he can abuse you again. Like I said before, he's textbook. And in the nicest possible way, so are you. The two of you have an absolutely standard abusive relationship. You've said nothing on the whole thread that would surprise anyone who is familiar with how abusive relationships work, and how they perpetuate.
The apologising even has a name. It's called 'hoovering'. And that's what he did when you tried to leave before. He hoovered you back in.
www.goodtherapy.org/blog/hoover-maneuver-the-dirty-secret-of-emotional-abuse-0219154
Are you still trying to find ways to not perceive him as abusive? Have you still got a bit of that 'He's not that bad, really', at the back of your mind?
If I punched you in the face, and then said 'Sorry, I realise I did it, and I'm so pleased with myself for noticing. There's something wrong with you, though, you weirdo... Why didn't you tell me it hurt at the time?!' Would it mean I hadn't punched you?