I seek legal advice in relation to my sons rights regarding

I seek legal advice in relation to my sons rights regarding divorce and a separation agreement. In particular, I need advice regarding his financial position and care/responsibilities with regards ***** ***** two children aged 5 and 7. My son has been married for over 10 years. With regards ***** ***** house, it is unclear at the moment who owns the house or the arrangement with the mortgage – my son is looking into this.
In mid-January 2015, my son was told by his wife that she wanted to separate because she thought the marriage was not working – since this time we have discovered that she has been having an affair with one of his close friends. It is unclear as to when the affair started but evidence suggests (text messages etc.) that the affair started before Christmas. From January to April 2015, my son and his wife attended marriage counselling. Since January 2015 they have been living in the martial home (co-habitating).
My son’s wife has asked him for divorce on the grounds of adultery but my son has been in too much shock/grief to be able to process the information let alone start a formal process to divide assets/child responsibilities. To date he has had two weeks off work due to anxiety and stress. His wife has also had significant time off work due to stress and anxiety. In the absence of my son submitting divorce papers, his wife has requested a separation meeting and has asked that both sets of parents be in attendance.
Any legal advice you are able to share would be most grateful.
Regards
Sue