[UK] Am I being setup to fail?

My company was taken over around 5–6 months ago, and during the lead-up to the integration, I was expected to do two senior roles at the same time. The expectation was that I would transition fully into the new role before integration, but the teams and people for that role had already started reporting into me from January this year, while I was still fully responsible for my existing role as well.

For months, I was effectively covering both jobs to help make the integration successful. I pushed through it because I wanted things to work and I’ve always been someone who overachieves in my role. In my previous position, I consistently exceeded targets and KPIs.

We’re now around three weeks post-integration, and honestly, I feel completely burnt out.

The biggest issue is that despite now officially being in the new role, I still haven’t had any proper onboarding, training, or structured handover. The previous person in the role is still in the company, but there’s been no real transition process. At the same time, I’m being expected to immediately deliver against strict deadlines and KPIs as though I’ve been fully embedded in the role for years.

Because of that, I constantly feel like I’m on the back foot. I’ve dropped the ball on things over the last few weeks, which is really unlike me professionally, and when I ask questions or miss something, I get comments like “you should know this by now.”

But the reality is, nobody has actually shown me a lot of the processes, expectations, or background knowledge I need to succeed in the role.

I genuinely feel like I went from carrying two jobs for months straight into a role where I’m now being judged on performance without being properly set up or supported to succeed.

Has anyone else experienced this after a company takeover, merger, or integration? How did you handle the burnout and the feeling of being set up to fail?