Am I the a-hole for being mad that my mum promised something and then has gone back on it

So my[17] mum[35] are having a bit of a disagreement right now.

Im in college and I've been looking for manakins too use, the college has some but none with arms and none in the right position. I wanted to get a junk one from somewhere and maybe just work off that.

My mum mentioned to me about getting Free manakins and said we can pick one up, im now at the 2 week mark for this project and im now just learning that she cannot infact get a free manakin, because the place apparently hasn't contacted her back.

I'd mentioned it too a classmate in passing and they asked probably jokingly if theirs any small ones that i can get one for her Cuz shes also working on something clothing-wise too.

I had this project planned around being able to get a manakin and then my mum got mad and asked 'do I look like im made of money?' Because I mentioned what my class mate had asked.

Then I went into my room, and she started mumbling outside it 'all these kids treating me like sh!t' and 'guess im a terrible mother' She's done this before so I snapped at her and told her to shut up and that she always does this and I know what shes doing.

We haven't talked again and Im feeling a bit bad about it, my mums having work issues and my sister is having issues. So idk I'd ask other people but I dont exactly have other people to talk too about these issues right now.

What do you guys say? :/