I've been in a new job for 3 Months and was invited to someone from my previous workplace's leaving drinks tonight, a few weeks back. Have a lot going on at the moment which I won't bore you with the details of, and so I totally forgot about it until an ex colleague (let's call him Ron) text at 7pm saying "Are you coming to Bobs leaving drinks tonight". Replied saying "sorry forgot but send my apologies" etc etc. I text Ron back a bit more catching up on the latest in or lives, and also text Bob apologising for forgetting. At about 9pm I was having a bath when I got a voice recording from Rons number. It was a woman's voice saying "I can't believe how much PiperChapstick is a fucking liar" 
I replied asking Ron who was that and why did they call me a liar. After much skirting around he said it was someone in my old office who doesn't believe I forgot about tonight. It was meant to be funny apparently and I'm being over sensitive.
AIBU or is this out of order? It was quite an aggressive recording, DH came through as he thought I was watching a video of someone fighting