I am so sorry OP for what you and your daughter are going through . Do not beat yourself up for what you have done to confront him and when you did it . You have done absolutely nothing wrong here , it was all on him .
I think in an ideal world we would would all wait " to get our ducks in a row " etc but that doesn't take into account the mental anguish and pain and suffering you experience when you have been betrayed .
The American site - surviving infidelity is often mentioned on this site so you should have a look through that .
As others have said , start some counselling for you and get a solicitor's appointment as soon as you feel up to it . If you have a close friend who would be willing to go with you for support that would be ideal .
Look after yourself and your daughter . I would try and keep your daughter out of any more of the details if you can . You can try and answer her questions , if she has any but I would try and be brief .she will also feel pain about finding out and how she did so .
Do the bare minimum , eating , sleeping , try and keep hydrated . Tell those family / friends who can support you .
I think you have to accept now , even though you have had a long marriage that your husband is no longer someone you can trust with the truth .
I have read about " cognitive dissonance " where essentially the cheating spouse will try and frame things in such a way that they didn't do anything wrong . They do so as they don't want to come across as a "bad person " even in their own mind .
You are in shock now , your H has checked out of the relationship and will be prioritising the OW .
I don't know what your position is about the marriage . That is not something you have to decide on immediately , or if you decide one way that you can't later change that . It may be that your H has already gone to the OW and that he doesn't want to work on the marriage . This could of course change when the reality sets in . You have to do what is best for you and I think you have to factor in not only the cheating but how your H is treating you now .
Take care . 

