So I (17) had been friends with this girl (16) that I met through my bestest friend. We ended up being a trio after a few months of being all friends, but I ended my friendship with her after she stole one of my pens. For some context, she was extremely rude towards me and my other friend, always insulted me and constantly ignored me. She had no filter at all, and didn't really put ANY effort into our relationship.

One of the things that made me rethink our friendship was the one and only time I took her and my other friend to meet my grandmother. After saying hi and all that, the three of us sat on the living room where my grandma was and we started painting and drawing. She, in the other hand, took out her tablet and started reading REALLY explicit fanfiction on there. I didn't mind, until she started getting bored and talked to us using very vulgar words IN FRONT OF MY RELIGIOUS GRANDMA. Both my friend and I told her to at least speak quieter, but she didn't listen, nor cared.

Quick time skip. A couple of months ago, I went on a trip for about four weeks with my family, and decided to buy them some gifts there. The first week I found a really cute notebook with her favorite anime on the front, with a bunch of stickers inside. I thought it was perfect since she was about to start going to college, so I bought. Obviously, that wasn't the only thing I was gifting her, since my original idea was to buy each of them at least four things. I sent her a picture of the notebook, and her response? She laughed at it said it was shit. Literally. She has always been ungrateful, something that I put up with since I didn't wanna argue with her, but it really hurt me when she said that. In the end, I only bought her that notebook and a plushie of her favorite character.

One more thing id like to add is that she ALWAYS chose someone else before me. ALWAYS. I was never her first option, but she was (almost all the time) my first option. Never wanted to play games with me but would spend weeks playing with her other friends, ignoring me but talking to our mutual friend, etc, etc.

So, even after putting up with her and her shitty attitude for months, I gave her one last opportunity. I invited her over to my house. One important thing I have to say is that I LOVE collecting pens, pencils, markers, etc. it's my hobby. If she'd ever ask me to give her one I would've said yes. But this time, I had to say no. She wanted one that I bought on the earlier mentioned trip from a store that doesn't exist anymore in my town, and it was very special to me. I offered her another pen, since I knew she wouldn't even use it, but she didn't want it. After she was gone, I realized one of those pens was missing (I had it stored on a specific case with the other pens from that store), and figured she had stolen it, since it was the one she wanted so much. I looked for it all over my room, but there were no signs of it still being there.

After ignoring her for a few weeks I told her, in the most polite way possible, that our friendship wouldn't work and that I wanted to end things with her. She apologized and stopped texting me, but I still think I overreacted. AITA?