Hi, My Daughter States That We Say Things We Didn't

Hi, my daughter states that we say things we didn't say. She insists that I called her horrible when what I said is that sometimes she treats me horrible. i never said she was horrible. Her brain doesn''t process sentences the same way ours does. She accuses her sibling of doing and saying things they didn't do or say. In her brain it is real. She cant read fast or communicate what she means very well. She is 15 and asks for simple things to be explained to her. Words she used to know she no longer knows the meaning of. she cries often because she says there is something wrong with her brain.