I killed an NPC and I feel bad and I don't know how my character would deal :(

So, we've just started a Descent into Avernus campaign. I am a newer player. We had another campaign that was three years long, but this is a new one, with the same people, and I am playing my second longer-term character. I am playing a Summer Eladrin Archfey Warlock. She's whimsical, a little airheaded, impulsive, upbeat, and mischievous. She snuck out of the feywild with the help of her patron is now on vacation. She joined a band. Our party is a band. We just got to the Vanthampur Manor in Baldur's Gate. It was full of guards so we decided that I would Mistystep into the stable, release all the horses to cause a distraction, and then sneak in. Unfortunately, there was an NPC in the stable, so I was spotted as soon as I hopped in. I panicked cast Friends to keep him from immediately blowing my cover. We chatted, he mentioned a trap door, I lured him over there, and, aware that when Friends ended he'd be mad, pushed him down the trap door. He fell down, and died.

I as the player, 100% did not think he'd die. I'm a newer player and you know, if a PC falls 15 feet, they survive, and I didn't quite realize how squishy regular people are in DnD. I thought I'd trap him down there for a while and we'd do what we needed to do, and then let him out when we all made our way down the trap door.

I think we're going to breeze past it but I feel bad. We're not a party who are normally like jumping around and murdering, and the DM specifically asked for characters who aren't evil and I just killed a poor old man. Especially because I could have done so many other things. I could have tried talking him into going down there, cast Sleep, whatever. I, the player, panicked. The other people weren't upset, just a little shocked. Nobody seemed mad at me, more of a did she just really do that?? I think the DM would prefer that I don't make murder a go-to tactic, but I don't plan on that.

I guess I'd just like advice. Less on how to deal with my friends, they're chill, more on how to deal with this in game. I'm newer to DND, a bad actor in general, and not well versed in DND lore. How out of character does what happened sound / how would you suggest I roleplay that / how bad should I feel? I feel like my character would not be above locking someone in a closet or in a trap door for a little bit to get what she needed done - she might think its funny or no big deal. But killing? Not really sure? Would Eladrin even care all that much? Like its just a human, do feywild denizens see those as playthings? Plus we've killed a few people before already right? Should I just let it go and not mention it again? I think if I didn't it'd be let go. Would this be something big enough to have it be a big character shifting moment? It's like session four or five so I don't know if I wanna do that if I can avoid it? I know this is ultimately up to me, but I am new so perspective, advice, and thoughts would be appreciated. Thank you!