My bf used our joint date fund to buy HIS MOM a gift??

Okay I need outside opinions because I'm about to lose it.

I'm late 20s, been dating my bf for 2 years. Since the beginning of our relationship we've had a 데통 (date account)¹. We both agreed, no pressure on either side, we each drop 300,000 won (~$220) into it every month and anything couple-related (food, movies, dates) gets charged to THAT card. Clean. Transparent. Worked great. Or so I thought.

So yesterday I'm checking the balance before our weekend date and. the number is WAY lower than it should be.

I scroll through the history and there it is. A 150,000 won (~$110) charge from a weekday. Location? The health food section of a department store near HIS office. I have literally never been there with him.

So I ask him, very chill: "babe there's a 150k charge on the date card, what's this, did you use it?"

Him: "oh yeah it was my mom's birthday recently and I left my personal card at home so I had to use the date card in a rush."

Okay. Fine. Mistakes happen. I was prepared to be normal about this. I smiled and said "okay cool, just put that amount back in later then 👍"

And THIS is where my jaw hit the floor.

He goes: "do I HAVE to put it back? we're gonna get married eventually anyway. my mom is basically your future MIL so just think of it as the daughter-in-law giving her a little gift in advance ❤️"

I'm sorry WHAT.

I said "what are you talking about?? this money is for US to go on dates. it's not even a gift for MY parents, why would YOUR mom's gift come out of joint money that includes MY salary?"

And bestie. BESTIE. He starts going off on me.

"wow you're so strict about money, such a turn-off. imagine if my mom knew you were fighting your boyfriend over a measly 75,000 won (her half)"

Like. Excuse me??? The audacity to weaponize his own mother against me for asking him to refund money he spent without my permission??

I was so stunned I couldn't even talk for a sec. Then I said "okay then can I buy MY parents 150k worth of gifts with the date card too?"

And THEN. He hits me with the financial hardship card.

"you're an only child, your parents give you plenty of allowance. you KNOW my family is struggling right now, I just wanted to do something nice for my mom and you can't understand that?? you're being so selfish."

I'm sorry. Isn't filial piety supposed to come out of YOUR OWN wallet?????

He used joint money without asking. Then painted ME as a petty gold-digging shrew for wanting it back. I'm so done. Like genuinely the ick has entered the chat and it's not leaving.

Am I actually being cold here? Am I being stingy to someone who's "going to be family"? Or is this a red flag the size of a stadium?

Please tell me I'm not crazy.