AITAH for telling an elder woman to “Get the f**k on” after holding up the only open line?

Earlier today I (28M) stopped at the grocery store while out running errands. There was only one cashier open for whatever reason, so the line was long. The woman (60s-70sF?) in front of me was talking the young cashier’s (18-21F?) ear off about her son-in-law (her daughter’s husband) after she had already been rung up with a receipt in hand. Apparently her SIL is a “deadbeat covert narcissist” or something. I could tell the cashier was too nice to cut the woman off, and she kept glancing at me giving me “the look.” The “I’m so sorry” look.

Look, I love making small talk myself, but this conversation had gone on over a minute with like 6 people behind me in line. I heard a woman behind me quietly under their breath say “Oh my goodness lady let’s go….” so I clearly wasn’t the only one irritated.

After about two minutes or so pass (two minutes after she already paid,) I calmly say “Excuse me ma’am, I have to be somewhere soon.” She looks at me with a cold face, wags her finger and says, “Um, no…you can wait.” The finger wagging honestly set me off and I raised my voice saying “Get the fuck on lady You’re not the only one in the fucking store, you’re holding everybody up.”

It got pretty quiet after that and the security guard walked over to me and said “Sir, please calm down, ma‘am please be aware there are other shoppers in line.” The lady finally walked off cursing but I didn’t catch what she said. Now for some reason hours later I’m here sitting at my desk feeling like a jerk. Did I go too far by raising my voice at an elderly woman? Personally, I just feel it’s rude to not be considerate of other people in line while shopping. You don’t know what kind of schedule someone’s on and I feel it’s best to not hold up lines, or at least step away if continuing a long conversation. AITA?