Hi mashed. Welcome on board.
I hope you stick around as it's so important women who have experienced this, talk to each other.
It sounds like your DD is around the same age mine was when her Dad and I separated.
I'll give you some advice which might be a bit blunt but which I think is sound.
Here's my take on your situation- by trying to control what he wears around your daughter and trying to stop her from finding out, you are still caught in the familiar cycle of compromise/ boundary pushing/ escalation that you were in during your relationship. You won't have managed to make him behave reasonably and considerably then, you've got no chance now.
Also you're allowing him to keep his role as victim of your terrible oppression
which he will have an online Greek chorus sympathising with him over.
I'm well aware of the stress and anxiety that is part of this situation and the affect it has on one's health.
You need to let it go and accept he is responsible for his own actions and you cannot influence them. If you try to control a situation you have no control over, it will drive you mad.
The relationship between your daughter and her Dad is now between the two of them. It is his to fuck up (and there's every chance he will).
It would be better for her if she knew and it was all out in the open. In your situation, I told my ex to tell her and he did. If you can't trust him to do this, I'd seriously consider telling her yourself- far better she hears it from you than finds out by accident. If he's indiscreet (as my ex was), she could even hear about it via gossip.
I hope this is helpful 