AITAH for going behind my boyfriends back and looking for a private doctor for his daughter and trying to force him to take my money

I'm (26M) my boyfriend is (27M). He has a 6 year old daughter from a previous relationship which he has custody of.

We are together 3 years. Live together for over a year but we knew each other a lot longer. I'm his daughter's godfather etc.

His daughter suffers from a back issue. The issue can be massively improved with surgery but there's huge waiting lists in public hospitals so they have been waiting.

I was genuinely sick of the waiting. Some nights she can be in really bad pain (it's always the night time). There are nights I'm up with her til 2-3 in the morning. I don't think she's ever without some pain. I wouldnt wish it on my worst enemy.

I said he should go private. He said he can't afford it. I said I'll pay. He rejected it outright. I said don't think of it as me paying to help you but me paying for my goddaughter. Its my job. He said no.

So I respected his wishes for about two days and then I went off and looked around. I thought if I had things in motion he'd change his mind. My brother in law works in a private hospital and he knew a great surgeon. I got the details etc.

I went back to my bf and a big fight ensued. I didn't respect his wishes (I didnt). He'd feel very uncomfortable. I said (which was probably nasty) I'm not doing it to make you uncomfortable but to make her comfortable. He said there will always be a debt. I said there's no debt. I said I'm not paying for him. etc. And do you know what I'm paying for myself too. No one wants to see a child in pain, me included.

We haven't really spoken the last few days but do you know who's back is still hurting...

I get the idea of pride. I get he worries about dynamics. But if we were not dating and I knew how bad it was I'd do the same thing. I'm not someone who rides off my money. I don't throw it around.

AITAH for going behind his back?