AITAH for breaking a commitment/favor after 2 months

my sister is having some trouble recently. like she is actually struggling i dont want it to seem like she isnt.

my sister wanted to have a project done and i agreed to do it. i said idk how to do so and so, so this may take a few months also im at uni etc. she said she would do one of the things idk how to do, so all cool.

im making fast progress with the earlier parts doing it in abt 2 weeks. i get to the part where i need her to do the thing she said she would do. she says its too hard and i should just do it. there was a tiny bit of back and forth bc that pissed me off but she just kept saying for me to do it. \*note: she has done it before, and its not like she tried and failed she just didnt attempt it\*

i slowed down drastically almost doing nothing. then maybe a week later uni work starts picking up and i say i cant rly focus on the project rn.

its been a bit under 2 months and she tells me to do an easier version of the project. i say cool. im on the phone with my nephew and she asks if i can do it and in short i say yeah i can do it (with the implication im gonna do it now or very soon).

i open up my laptop to start and i decide to do the connections nyt thingy first. im talking to my nephew while doing it. if youve played it yk it takes like what 10 mins? maybe a little more or a little less. id also just woke up recently so i just felt like doing it first idk if i have to defend myself abt this or not.

so she starts talking to him after im towards the end of the connections thing. "you dont care about mummy bc mummys life is falling apart and you dont care" thats not an exact quote bc memory but it was something along the lines of that. he asks her "well mumma what was i supposed to do… for the uh thing you just said" (thats almost exactly what he said bc i remember the pauses of him just being confused). she then says somethint along the lines of "youre talking to (my name) and encouraging her to play a game while im struggling"

so i just felt rly uncomfortable there and said hes not making me play connections i just felt like doing it first?? and she starts going on about how i didnt tell her i was doing it first initially, which is true, but she knew i was doing it for the past however long bc she can hear us talking abt it.

i then quit the project and just said im not doing it if im being interrogated and guilted for doing a word puzzle before i start. it became a whole blowout of how im treating her like shit and my actions show i dont care about her and that i want to make her hurt and she cant have a relationship with someone who would break a commitment and she would never promise something to me and take it back and its a really low thing to do. these are direct quotes bc it was messages not over the phone.

anyways yeah aitah

edit: changed the words about to make it less confusing