Try to sheild her as much as you can. My D13 hates (I mean really HATES) my W, if my W is over at the house to pick up or drop off S9 it makes my D13 physically ill. D13 is in therapy for all this. I feel responsible but know ultimately it is my W's fault for what she is going through.
I will say this, your D11 will ask one day when she is older whether you and your W reconcile or not. IMHO, we owe them the truth maybe not all the technicolor details but definitely not lies to protect the WAS. If your D13 has ill feelings towards your W it will hamper any reconciliation process.
Formerly "missherlove"
Me49 XW49 M17 T19 S16 D20
Expose yourself to your deepest fear; after that, fear has no power, and the fear of freedom shrinks and vanishes. You are free.
