My apologies I have been offline whilst travelling
I have now also read the other thread that your had opened with copies of the letters
I am sorry but I am going to have to be very blunt with you.
The emails he sent were not just a breach of the non molestation order they were inappropriate in every way to send to a child and would have entitled his ex to make a new applictaion to the court had she wished to do so.
However it seems from the letter from her solicitor that she does not intend to take action - so on that at least you can relax
However by giving up the ocntact that he has your husband is making it much much harder to have any contact with the children in future.
Yes it is hard to only have weekends - and of course the children so not wish to go back - it is also normal for the children to then carry on without contacting their father in between times.
This is how children manage to cope with living separately with each parent
It is up to your husband - the adult - to understand the needs of the children - to have a wonderful time with them when they are together - and to reassure them that he will be there next time - and that he does not need THEM to support him.
Please look at this website
To try and ensure that the ocntact is resumed with the children at the centre
I am so sorry to be harsh - but it is clear that the children love their father - and need him