AITA? My Girlfriend keeps wearing the jewelry her ex gave her and it’s driving me crazy

My girlfriend loves shiny things and jewelry- I understand lots of women do and that’s ok. They’re supposed to dress up and attract a mate, I get it. She has actual heaps of sparkly objects- chains and earrings and rings and brooches, and she’s always browsing and looking for more. Nothing too expensive, I’ll give her that, and she does look lovely when she’s all dressed up with something pretty dangling at her ears and neck and sparkling on fingers. I also soon found out that the best way to make up with her after a fight was to pick up something sparkly for her – she can barely resist me once I gift her a nicely wrapped jewelry I’ve picked up for her at the mall. And I have to say, with one thing and another, we do have our fair share of quarrels and so the pile of shinies I have given her is growing bigger.

I have noticed, however, that she doesn’t always wear the trinkets I give her- I understand- our tastes may differ and that’s ok. But then she casually mentioned some of the stuff that she wears regularly is actually given to her by her ex. Who, as far as I can from her dropped hints, was absolutely psycho.

Now, don’t get me wrong Reddit, I am not some jealous crazy asshole. It’s just that I don’t understand why she would wear jewelry from her ex, whom she has mentioned several times was an abusive, manipulative, and eventually violent psychopath, but not wear the stuff I’ve given her. I have bought her nice big baubles which she has barely worn once, and meanwhile, the thin, barely-noticeable bands of weird twisted metal which she casually mentioned were a gift from him- she is always wearing them! What’s up with that? If he was as abusive as she says he was, why would she keep wearing the stuff he gifted her?

And I’m not going by her word alone, I’m a meticulous guy and I’ve done my research. I’ve looked into this fella, and apparently, he is as bad as she says he was. Which makes it even worse! Clearly, there’s something to be said for this whole idea of women being attracted to bad guys: here is my girlfriend, clearly still carrying a torch for her psycho ex, while disrespecting, me, her nice and gentle boyfriend who would never lay a finger on her.

At this point, Reddit, I feel I am fully justified in poisoning the jewelry he gifted her and letting her suffer the consequences of her disrespectful actions. As I mentioned, I am nothing if not meticulous, and I can use something which would give her a mild rash, all the way up to full-on killing her within minutes of putting on a pair of earrings.

What do you recommend?