I (17F) have been friends with the same group of four people since fourth grade, June (16M), Lila (17F), Ryan (17M) and Marianne (15F). Back during middle school we all noticed that June had a lot of trouble during school when it came to studying for tests and no matter how well versed he was on a subject he consistently scored in the 30-50% range, so in the fifth grade we all decided to help June during the tests. We all came together and put together a secret 'language' to help June out during the tests through a series of clicks, taps and coughs, yes we are all aware that this technically counts as cheating but after just implementing the technique over the years his test scores improved greatly and he's even made honor roll. The problem arose at few weeks ago when Lila introduced her cousin Lucy to our friend group, Lucy is nice enough and I've seen her passing a few times before, but to be honest she's not my favorite person. She finds it funny to make fun of June's speech impediment and consistently tells him how 'stupid' he is for not being able to sit still. June has gotten a lot better at studying but we still use the code because classes have gotten harder, I think Lila told Lucy about it because she came up to me and asked if I could teach her the code because she was really struggling in our APUSH class and needed help (I'm the only one she shares the class with). I told her no and that I didn't want it to get out because I didn't want to get caught, but in reality I really don't like her. I told Ryan and Mari about this and they agreed with me but Lucy told Lila what I said and was angry for not including her cousin, especially when she was in a new school and having trouble making friends. She said this could've been a bonding moment for her and the group but I honestly don't want her anywhere near the group or me. I get that she's in a new state/school but I can't get over how she treats June. I'm really conflicted and I can't tell my parents without getting in trouble.

So AITAH for not including her?