Wife answered call from work while I was on leave telling them not to ring, now I have a disciplinary hearing

Hi, I was supposed to be off last week to spend some time with my wife. I work as a platform engineer for a large MSP, and part of that role includes covering work out of hours and on call. I was supposed to be off last week, and but we have some management based out of the country who keep just randomly scheduling us without our approval or checking for when we're on holiday. So I wasn't expecting to be called while I was off.

Anyway, while I was off there was a critical incident on one of our customers, some kind of production outage that was going to cost our MSP heavily in financial penalties because it had been going on all day, and they saw I was "on call" and rang my work number despite me having an out of office notice in.

When my work phone doesn't answer, it forwards calls onto my personal mobile + I'd forgot to turn off the divert, and my wife took a call from work while I wasn't in the room and yelled at them for ringing on my week off and not to phone again. I wasn't there when this happened, and all she told me was that work had phoned by accident forgetting I was off so I went and turned my divert off so I wouldn't get any more calls.

When I came back on Monday my line manager who is based outside the UK pulled me into a call with the UK account manager asking to know what happened. It was very demanding how they worded it and when I asked for some context they said "can you tell us if you're aware of any calls received over the weekend", and that went into a back and forth as I explained I was on leave and shouldn't have been called, and that the one call I was aware of my wife told the person ringing I was off and that was it. I was told my wife was rude and shouted at the phone, I asked for a transcript and they sent it to me, and they said it was a massive security breach because information had been disclosed to my wife over the phone... but I would say that I can't really help that when they shouldn't be phoning or disclosing stuff over the phone. The agent (the service desk is based offshore, so I dont think they recognise gender neutral names) literally opened up with "Hi XXX, its XXXX from XXXX, we have this issue with XXXXX"

Now I have a call logged in the diary tommorow morning with the account manager, my line manager, the org manager both offshore and someone who seems to align to HR. Am I in a good position to defend myself or is gross misconduct something that could end up being slapped at me here?