Madmixtress,
Well yes you are in danger of coming under fire from wives who have been left by their husbands for new girl friends.
A couple of thoughts....
I really do not feel that you can label his wife petty or vindictive. She has just been betrayed by her husband. The shock of losing your husband can be very severe and a week is not long enough to get over it or to start acting rationally.
The child contact issue you raise... 1 week is way way too early to begin instigating contact between you and her kids. You just took her husband - of course she wont let you near the kids. What if you and he split up in 1 month and he goes back to his wife. It wouldnt be the first time.
You cannot expect to move from the old status quo to a new settled situation in a week - it will take months/years.
A couple of things you mention give the impression that you partner is reasonably well off. This means there could be a lot at stake in settling the financial aspect of the divorce and it could easily take a year or more to be settled.
You say he is prepared to be generous - the law entitles the wife with 2 kids of a high earning husband in a reasonable length marriage to a very good settlement (lions share of assets and high maintenance) - what he now thinks of as generous may actually turn out to be a lot less than she actually gets awarded.
Yes you can be named on the
divorce petition though it is more normal these days to mention adultery with an unnamed third party. If you are named you may find that just delaying returning the petition stalls things and she will get fed up and take your name off.
The issue of access to the house is a common one and a messy one. The legal position is that yes he is entitle to access the house until she puts in place some kind of injunction to stop him.
In practice if he goes round and tries to get in causing a disturbance then she will likely call the police and they will turn up and strongly encourage him to leave.
Really the home access comes down to letting things cool down to a state where she is less in a state of shock and a sensible practical arrangement can be made for perhaps a mutual friend to go round to pick some stuff up for him.