But you shouldn't have to. Your Soilder 76s and McCrees should be taking her out or at least lowering her enough to keep her out of the sky for long periods of time. DVA should be on the ground mostly unless you boost to get to another position.

Get close enough to her to chip away. Try to scare her, poke at her a bit then get back into healing range. After that hopefully the rest of your team is smart enough to take her out.

If you have a Widow pray she's not trash (pray hard because most of them are useless)