Yellowrose I really feel for you. I can feel the conflict coming off your recent posts, between your wish that he would behave in the way you are hoping he will, between your desire not to hurt him/upset him, between feeling it's your fault. It's a lot of conflict to have swirling about and I can imagine (because I've been there) that it's pretty confusing.
Here's my thoughts, as someone who has recently been trying very hard to stop being a people-pleaser and build their own boundaries.
You are worried, I think, that if you take the bull by the horns you will feel terrible. Because he will do his damnedest to either make you feel guilty with over-the-top promises, or make you feel rejected by seeming not to care if you are breaking up. You are, I think, waiting for him to make a move in the hope it's the one you want to hear. But by putting the power in his hands you lose your voice.
You said: I want him to know this behaviour is not OK and that I am not accepting it. You will not get the resolution you are looking for unless you create it for yourself.
You want him to admit he's not behaved very well and apologise. He wont, I doubt. (In the same way he hasn't actually yet apologised for upsetting you with the name thing - what he said on text was just a reaction to you asking for an apology, and was of the 'I'm sorry you are upset' variety. He didn't actually apologise for upsetting you or make right what he'd done.)
You can't make him know anything. All you can do is tell him how you feel. (Which you already have, several times.) In my experience, looking for them to somehow realise how much their behaviour has hurt you is futile, and ends up with it being projected back to you and it somehow becomes your fault.
You are worried, I think, that if you take the bull by the horns you will feel terrible. Because he will do his damnedest to either make you feel guilty with over-the-top promises, or make you feel rejected by seeming not to care if you break up. You are, I think, waiting for him to make a move in the hope it's the one you want to hear. But by putting the power in his hands you lose your voice.
I think if you text him saying anything at all like 'What's up/what's the deal/why haven't you contacted me' then he'll either feign complete innocence, leaving you feeling like you've overreacted, or he'll say something to make you feel guilty - eg 'I assumed you'd gone off me because you didn't want to see me on Sunday and haven't been in touch'. Both of these replies leave you scrabbling to justify your behaviour and put you on the back foot.
So. Now is the time to decide whether you want to continue or not. If the answer is no, then a text is fine - 'I've been having a long think about things after our argument last week, and I think we are just not right for one another. All the best.' No point in trying to get him to admit to anything, he never will, and trying to get 'closure' on why he behaved how he did will just confuse you more. Also, no need to justify why you are ending things.
Or you decide you are going to continue, in which case you need to set your corner out now - 'I haven't heard from you all week since you cancelled our Sunday plans, and I still haven't had a proper apology for the disrespect and upset you caused through not saying my name properly. These things are unacceptable to me, if you want a relationship with me we need to talk.'
Either way, take control in the way that you want, so you can stop the spaghetti-head feeling. Don't wait for him to decide what you do. You can do this. 