It's not a projection, and I haven't read incorrectly, you said it was 'agreed' that you wouldn't pay rent, because 'that hasn't changed when you moved in'.. while that is factually true.. IMO anyone who thinks like that is quite selfish in their thinking to be honest, the whole point of sharing your life with someone is to also share the burden.. you were both earning the same at that point, and I personally couldn't see my partner having to pay more just so that I could benefit from paying less.. it is personal opinion, but I think it quite universal when you are both earning the same, but he has more financial obligations.
so I covered all food all activities, all clothes, everything that was needed for the week, including keeping DSD fed watered and entertained.
I'm sorry but if you weren't there it is highly unlikely that he would have been spending all that on her the month after christmas, because he just doesn't have it, and she would have survived perfectly fine, you really are confusing essentials with luxuries.
You have chosen to spend all that on her knowing he can't afford to pay it back.. if she comes and says she needs clothes he will have to find the money for that (probably with more debt that he is trying to avoid), but don't send them back to her mums if you don't want to lose them!
There is not really a right and wrong here, but there is a massive difference in financial positions.. you think you can spend whatever you like and he should be able to instantly pay it back, but he is obviously in more of a precarious position then you are aware of.. no one should be planning a family without laying all this out on the table, and you seem to have skipped that very important part.
I know this sounds condescending and I actually don't mean it to be, it's a genuine question, have you ever lived on your own or supported a household on your own? You seem to not understand how someone could get into debt or not have any disposable income and have to live month to month? Once you start to acquire debt it is hard to get out of it and can become quite an embarassing / shameful thing to live with. Someone coming along with lots of disposable income and no understanding of what it takes to run a household, yet happy to spend money you don't have is not really helpful.