It sounds as if she is acting out and testing. It's actually a good sign. Because it probably means she is wrestling with emotions. She needs to know if your change is genuine or fleeting. If your change is fleeting you will revert back to your old habits and she will know not to become emotionally invested. If your change is genuine she will begin to accept it.
She has been with you for a really long time and seen you "change." She has a right to be suspicious and test the waters. You should want her to do this. It's a sign of emotional stability. Someone who is not emotionally stable would jump back into the relationship without giving it much thought. The shear definition of insanity.
Respect her anger. She has a right to anger. Anger shows emotion and passion. I would be more concerned if she wasn't angry and lashing.
What I don't like is your wife taking it out on the children. Lashing at you is one thing. You are her partner. This is what you are there for (to catch her when she falls)
Lashing at the children is unacceptable. As the head of the home it is your responsibility to take your wife to the side and gently point out that your children are not targets for anger--for either of you.
Lock this down now.
Be loving. Be gentle. But be firm.
Your daughters are learning how husbands treat their wives by how you treat your wife.
And your daughters are learning how mothers and fathers treat their children by how you both treat them. Children do not forget. To the contrary. Children are sponges. They absorb.
Your wife should be reminded that you both have a shared goal: To raise wonderful, well-adjusted children who will also raise wonderful, well-adjusted children.
This will not happen if their parents are not keeping promises and disrupting their lives by ruining family gatherings like picnics.
Small moments have lifetime consequences. Ask her to please respect your children's right to a peaceful home during this time of turmoil.