A company is a company, your manager is in your team, the product owner is in your team, the salesman is in your team, the CEO is in your team. Talk to your manager, and your manager will talk to the stake holders to see what to do about it. Delays happen all the time. No biggie. Just try and understand what went wrong (to make sure the next one doesn't suffer the same) and how much time it will be costing. They'll be asking you anyways...
If you're in one of these companies where people are not allowed to screw up, then I would recommend you start looking for a healthier work place.
Exactly. Managers manage many things, including expectations. Make sure your manager and you are on the same page about schedules. Then let her do her job while you do yours.
If your manager decides to blame you, rather than defend you and your team, it's resume time.
Managing up is the most important thing a project manager can do ("shit umbrella vs shit funnel") - if they haven't been communicating the actual status of the project then they haven't been doing their job.
If they don't know the actual status of the project then they haven't been doing their job either.
If you're in one of these companies where people are not allowed to screw up, then I would recommend you start looking for a healthier work place.
Good luck