Honestly, breathe. This isn't entirely on you - your company should have more safety nets than a trapeze artist. If they handed you the keys to a £104k budget without any guardrails, that's on them, not just you.
At our place we've got three layers of protection so this kind of thing doesn't happen. First, we set a monthly spend cap whenever budgets change significantly. Second, we've got a script that pings a Slack channel every week with spend data, and if an account goes over a threshold it tags people and sends emails like a panicked parrot. Third, weekly sit-downs where the PPC lead walks through the account with the account manager. Yeah, I'm paranoid about overspend too - for good reason.
But even if all three fail, we've got insurance for this exact nightmare. We'd try to fix it with the client first, and if that falls apart, insurance kicks in. So if one of my team did this, I'd be pissed, trust would take a hit, but I wouldn't fire them. I'd work through it. You don't give someone 25 accounts if you don't trust their ability to bounce back. Own it, steal our prevention system, show you're still invested in the work - you'll be fine.
Also, the client is almost certainly not getting every penny back. They'll push hard to squeeze what they can, but they'll settle for something like free months or a partial refund. Most agency contracts cap liability anyway. They know the game.
Sorry your personal life is also getting shat on right now. Hope this takes some weight off.