I'm starting to split big time on my close friend. We usually hang out at least once a week maybe more but last weekend I was busy and had already made plans which she knew. She continued however to text me with plans like to swim or hang out and I stopped replying after realising she didn't seem to read those messages because on Sunday night, she then passively aggressively told me she was alone on the weekend and I need to be better at planning.... ummm what?! 
Now today she has already texted 3 times asking when she can pop by mine and I said I'd let her know and now she's texted twice again as if I'm obliged to give her an answer immediately. She also kept questioning what I did and who I saw on the weekend which tbh is not her business right? Since I did stuff with friends who don't know her. 

She's a good friend and does have adhd however this clingyness is really making me split to the point I can't even bear to reply her back