I am in your friend's position. Friends and family have literally been life savers for me.
Go over to her house, pick her up, take her out whether she wants to go or not. Take her out for coffee, or a diet coke, anything to get her out.
Hugs are super fantastic in this situation, but if you don't like to hug, just listening to her is the next best thing. Buy her a box of Kleenex and just listen, listen and listen. She needs you now, just to listen and dry her tears. It is very painful at first even if the guy has been a boob. Eventually she will figure out that this was the best thing for her. If her husband was really as you say, she will eventually be thankful this happened.
She is afraid of what the future holds. She has pictured her future with her husband for so long and all of a sudden that picture has been destroyed, and she can't visualize what lies ahead without him. She is worried about a zillion things that she never thought of before, money, taking care of the kids all by herself, car care, house maintenance, mowing, working more, how to spend Christmas, Valentine's Day, dating, dying all by herself, no one there to hold her hand if she is in the hospital, what will she do Friday nights, retirement. The list is absolutely endless.
You need to be there for her to tell her to take it step by baby step. Tell her you will be there no matter what, friends are like that, husbands that leave, AREN'T.
Continue to invite her out and invite her over to your house to watch movies and eat popcorn. This will show her that you empathize with her, and she is always in your thoughts. Sending "thinking of you" cards is also a great plus.
As I said, this is a super super hard time for her, it is just as if someone has died. It's the same type of grieving process. It will take time, months/years to heal. It is a slow process. Her life is a roller coaster. Right now she is in a dip, eventually it will start to go up. She will continue to have more down days at first but eventually the up days will be closer together and last longer. She will find herself feeling more independent and a much stronger person.
She can do this, you can help by just being there for her. Another thing to watch out for is her talking about suicide. If this happens, get her help and fast.