Will my 7 year old cat always be mean?

So my female cat is 7 years old and I forgot how bad she was as a kitten I guess I always viewed her through rose colored glasses because I loved her so much. I remember the vet telling me that she was "feral" and that really made me mad at the time! How could he call my sweet baby feral lol she really only let me pet and love on her and a select few in my family. Now I have brought two kittens home. She has been super mad. Growls and hisses every time she sees them. She used to be an inside/outside cat but since the kittens have been here she's been strictly inside especially since the last time she was outside she got a wound on the back of her neck so I wanted to make her an inside cat. I will be making them a catio very soon and was hoping she could hold out in time for that. This wound hasn't been healing and it's been a month because she keeps scratching it open. Well I tried to put a sweater on her and then a cone to stop her from scratching it open but every single time I try to grab her now she screams at the top of her lungs!! Like I'm trying to hurt her but I'm not! I just don't know what to do with her now. Will she always be this way?