she has a track record of not contributing to group projects, and this isn’t my first time with her. as much as i try to be understanding, when it comes to deadlines, we usually set a date for our own parts to be finished and this is usually a couple days before the actual submission of the project. she never heeds that deadline and oftentimes does her part right before the actual submission - which i just detest doing because i feel the quality of work is compromised. 
it’s not like she doesn’t reply in group chats or gives ideas about the work, she just does not do her assigned part. 
the thing is - she has ADHD. she isn’t secretive about that and i know she needs more effort to do work. the other day, my friend was ranting about her and said something along the lines of “just because she has ADHD, everyone’s gonna brush off her mistakes and she never gets any consequences”. hearing this did make me uncomfortable, I don’t agree with the way my friend used her mental disorder to belittle her, if that makes sense.  
another project is due soon, and she has not done any work despite our group-set deadline being a couple days back. i got pissed and just sent her a chain of messages, basically commenting on her lack of responsibility to do work, and telling her that whether she chose to do the work or not wouldn’t affect us - the rest of us would just make up for it. but after sending that i felt, basically like an asshole. 

TLDR; group member never does any work, but she has ADHD, was i wrong to scold her lack of responsibility because i should be more understanding of her mental disorder? 