It's unfortunate.
You have some networking to do.
You could contact on your former manager, and assuming that your former manager was promoted upwards or moved laterally, ask them for their assistance and backing to move to another position within the company.
If your former manager is not in a position to help directly, ask your former manager to recommend personnel who could help you move to another position within the company and to explicitly put in a good word with this personnel on your behalf. This personnel might include your former manager's manager at the time.
If your manager is asking from each member of your team for unreasonable output and setting unreasonable deadlines and milestones for this output, she is setting herself up for failure, for which she will no doubt blame everyone of you. She is going down. Make sure that she is not taking you down with her. Collect references from anyone but theirs. Apply for suitable openings wherever you can.
Do some investigative research.
- Find out how she ended up on your team. Your former manager and if you have a good relationship with your manager's manager, might be your best sources of information. The reasons and circumstances she got in may very well be the reasons and circumstances she will be made to resign. For example, if she was given the management of the team as a last chance to prove herself in the organization, she will eventually be made to leve the company because she blew that last chance.
Take unified action.
- Have a team submit a unified petition to your manager's manager, with the complaint that her aggressive milestones and deadlines as well as the scope of her demands are setting the whole team up for failure. Note to your manager's manager that she has failed to provide any kind of logistical support to achieve these milestones and deadlines including allocating more human resources, and working out more achievable priorities on key tasks and more flexible deadlines on the less key tasks.
Have a team submit a unified petition to your manager's manager, with the complaint that her aggressive milestones and deadlines as well as the scope of her demands are setting the whole team up for failure. Note to your manager's manager that she has failed to provide any kind of logistical support to achieve these milestones and deadlines including allocating more human resources, and working out more achievable priorities on key tasks and more flexible deadlines on the less key tasks. Ask at the minimum that she makes an effort to work with you on what can be done instead of dictating the impossible to you.
As a team, keep the lines of communication with your manager's management open. If she knows that everything she says and does gets re-transmitted at least one level up, she may cramp her style. If she doesn't, she may be on an accelerated path out of the company.