I understand completely....it is not fair to you to be the brunt of her anger. I am not encouraging for you to give in at all....just say sorry and leave it at that. I thought the flowers may be a nice gesture and break the ice. Even nicer if you don't normally do that so it will be unexpected too
How is she doing health wise? Is she seeing her doctor? Is she on meds and/or therapy? It does sound like she should be seeing someone to work out these issues she has.

Heather
"The Pessimist complains about the wind, the Optimist expects it to change and the REALIST adjusts his sails." ~~~author unknown