Hi Beebers,
Of course you are going to be struggling with this woman. It may have been your husbands responsibility not to hurt you but she is the reason he hurt you. If that were that, if she were gone, then you'd be so far down the line today in getting over it. But she's still around. And what is more, she is around your children. That does not allow you the space you need to come to terms completely and move on. Its understandable, your children are possibly the greatest love of your life and she has access to them. You are handing over the people that you love more than anything or anyone to a person who has hurt you more than anyone or anything.
I would pay no mind to her look of smugness as and when you see her - that is going to be short lived for her. Life has a funny way of not allowing a person to be happy on the back of another's misery.
If I were you I would practice being helpful, happy and lovely to her when you saw her - no matter how much this is going to make your insides cringe and your head scream in pain. Because ladies like this, they do not know how to respond to that sort of behaviour. They are expecting conflict, bitterness and you to be very off with them - after all, look what she did to you?
I would never allow the other woman to see one moment of angst cross my chops. Even if it means I returned to my car after drop off of children, drove around the corner, pulled up and sobbed. They, she, is not worth it.
There will be no compassion in her for you. She's probably telling herself she is Kathy to his Heath and that justifies her behaviour - that's a long, long way to fall when she falls.
In the mean time, you have to pull up your boot straps and begin to live again, however small the steps are at first. Its like anything else in life that seems insurmountable. Take small steps, do one thing at a time, do not expect great things of yourself all at once. You think you can't do it but you can do it. If you are struggling with the children on your own, think up a plan, a routine that might better help you and them and also - don't be thinking that outside your life, others lives are great, others are managing, others seem happier than you - because they are not. There is trouble and strife in every life. People just hide it well.
Keep smiling