When I Accidentally Ruined My Lab Partner's Day

So, there was this one time when my lab partner and I were working on a project for our chemistry class. We had to mix these really precise solutions and get them right or else the whole experiment would be off. Anyway, it was pretty late, like 10 pm, and we were both feeling super tired. My partner was trying to explain something about the solution ratios but I zoned out because my mind just wasn't in gear anymore. The next day, I had this idea that maybe if I mixed in an extra bit of one component it would balance everything out or something. So I did it without telling her because we were running so short on time and I thought she'd probably get stressed about changing plans at the last minute. Well, turns out my theory didn't work at all. Our results were way off and I could see she was really upset when our professor pointed that out in class. She's usually so good with these kinds of experiments too... And ever since then, there’s this weird tension between us whenever we're together. I've been trying to figure out how to fix things but every time I think about it my palms start sweating and I get this knot in my stomach like I'm gonna be the one who messes up again. Should I just apologize or pretend nothing happened? It’s driving me crazy because she's also a really good friend outside of class too.