<human>: Give me the gist of the text in a nutshell

Throwaway because we both use reddit.

Background: me and my girlfriend have been together a little under five years. We live in different cities but they're close enough that we see eachother pretty much every other weekend. For what's technically a long distance relationship we get along amazingly and have never fallen into any of the LDR issues we were warned about. We've even discussed marriage, when she finishes her doctorate.

Anyway on a weekend we were together, I'd just driven 2 hours to see her so we generally just order a takeaway and watch TV. We were pretty much idly flicking through stuff when she said, out of the blue, "do you ever think about how you could easily kill me, if you wanted to?" I pretty much freaked out, haha. Asked her what the fuck she meant by that. She tried to play it off like it was just some funny thought that popped into her head and started fake-laughing and shit but honestly it didn't seem like a joke. In that moment she seemed incredibly serious.

I dropped it because who wants to be the guy who can't let a joke go but it's been playing on me ever since. I stayed up till 5am that night with it going over and over in my mind. We've never really talked in specifics about past relationships - just in very vague terms. But when she's been drunk she's mentioned an ex who once broke into her house after she broke up with him. She tells it like a funny story but I always felt like there could have been something more violent going on there. Selfishly, I guess, I didn't think about it much till now. (If I'm honest I don't think I wanted to - the thought of someone hurting her kills me.) Now, I'm wondering if she subconsciously categorizes me with him. Or if I did something to make her do that.

Please tell me what you guys think. Even if it's just that I'm nuts for overreacting to an off-the-cuff remark, haha. I'd really like to just get another perspective on this.
<bot>: gf asked if I ever thought about how I could kill her. She said it was a joke, I'm worried it meant something more.