She is trying to avoid communication w/you and is using the children to relay messages. I would choose a time and advise her that "we" shouldn't be using the children to relay messages back and forth. Another thought is that her phone was not charged and it was easier to have your child relay the message. However, many of them attempt to put the children in the middle and the best way to handle this is to use the "we" word about not using the children as messengers.
As for her replying to your message concerning the poor mouse, maybe she had something else to do...but it could also be that she didn't consider the message important enough to respond back to you, i.e., there was nothing in it for her...but having to deal w/the fall out of a child losing a pet and she didn't want to deal w/it.
I'm not surprised that she's gone out and purchased games. She wants to appear to be the Disney mom and make her place a fun place to be. Some of them do try to compete w/what a child has at home and most likely she doesn't correct them all that much. It's typical behavior for some of them.
Keep the focus on you and your children. Try not to allow her behavior to get under your skin.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
