Girlfriend blew up at me for calling her cat "it" and dragged my mom (who just had major health issues) into it — I'm done

TLDR

Look, me (27M) and my gf (22F) have been through nonstop ups and downs in this long-distance thing for like 2 years. I've been the idiot fighting tooth and nail to keep it alive every time it was basically over. All the energy, the emotional investment, trying to fix shit when it was dead in the water... and now this stupid fight has me feeling nothing but anger and weird numbness.

We were just casually talking about her cat and I referred to it as "it." She immediately gets pissed and starts going off. I tried justifying it calmly — I said since the cat is neutered, using "them/they" works fine as neutral. It's a cat, not some deep personal attack. But instead of letting it go, she hits me with this wild comparison: "If your mother had a hysterectomy, would you call her a she or an it?"

Bro, what? My mom went through some really serious, life-threatening health stuff just a few months ago (hysterectomy included, lots of complications and pain). Bringing her into a fight over a fucking cat? That level of zero care or thought for my family just destroyed whatever was left. I don't get why she took it so personally — it's an animal. I wasn't being mean, I was just using normal language and even gave a reasonable explanation with the neutered part.

Now I'm sitting here feeling kinda weird. Not sad exactly, just angry and done. This relationship has had way too many downs, and this one feels like the final straw. I'm at the absolute end of my patience. I really don't want to give it any more chances. After putting in so much to revive things before, it sucks that it ends up like this... but honestly, the idea of ending it doesn't even make me feel that different. More like relief than anything.

Anyone else hit this point where one dumb, insensitive fight makes you realize you're completely checked out? Should I even bother forgiving this or just pull the plug once and for all? Rant over, thanks for reading if you made it this far.