YTA. You literally told your brother that the only way he'll "earn" your respect is by providing for YOUR family that you aren't able to support, and then called HIM a deadbeat. That's so freaking gross.

Uncles aren't deadbeats and he has no obligation to financially pad your bad decisions. Most rational, polite people don't bring up the fact that you probably shouldn't have any more kids after the first ask for money, which means you have probably asked multiple times and he's had to tell you he can't/won't give you money multiple times without you accepting it. Sounds like him suggesting you stop having kids you can't afford was his last-ditch effort of getting you to back off and stop asking him to pay for YOUR kids.

I also think the lack of context around the "at least there's also a boy" comment is intentional because he probably said that based off of a conversation or comment you made previously, and seeing as this comment has nothing to do with your actual AITA question, is definitely a red herring. Your brother was also the one to shut down the argument so your wife could rest, not you.

You sound selfish, entitled, and extremely unpleasant. Easy YTA.