As you're really not going to leave him now, please can I ask you to very seriously sit down and WRITE down (not just think) what it would actually take for you to definitely leave him at this point. Write down everything you can think of, including the most extreme and ludicrous and the most minor things that would ACTUALLY make you leave. Things related to you and things related to your daughter.
The more minor things that occur to you that you waver about adding to that 'definitely' list, add to a separate "maybe" list.
Consider in what column you put the things that have already happened, if either.
Then put the list away for a few days or a week or so.
Come back to it and try to consider the list with fresh eyes as though it had been handed to you by your mum or best friend or grown up daughter re their own relationship. What would you think of it? Consider any category moves between 'definitely' and 'maybe'.
Refer back to it any time something makes you uneasy. See if that thing is already on your lists and tick it if it is. Add it if it's not and tick it.
Keep referring back to the list over time and keep it updated.
Take note if you start to want to move your 'definitely' items into your 'maybe' column after they've happened or as the relationship goes on (your boundaries are eroding).
Take note of how many maybes have been ticked over time (death by a thousand cuts - how many maybes will it take you to decide it's a cumulative 'definitely?)
If your mind starts to slide away from your original intentions and reframe and downplay things, this is one method of allowing you to see in black and white if your standards, rules and boundaries start to slip as you get in too deep.
Hold yourself accountable for your sake and for your daughter's.