Okay ... Humour to serious...
This is a brother's solution / advice to his newly married sister...
Take Preventative Measures...
1.) Add the Filter
2.) Have only one computer
3.) Have computer in common location - Family Room / Kitchen
4.) Have monitor / screen facing the center / centre of room
5.) Place keystroke monitoring software on the computer
6.) Do more things together so your not on the computer..
7.) Keep him busy with a Honeydew list (Honey do this, Honey do that..)
Reactive Measure (Use only if you are sure)
**IF** you see this again
1.) Confort him - show him the evidence
2.) Show the most extreme displeasure (do your worst) you know to him so that his brain makes the connections between his behaviour and this reaction
3.) Tell him you want a divorce and that you will tell his closest female relatives sister/mother/aunt AND the Imam the reason why you want the divorce
4.) If he repents sincerely, forgive him - if he denies it - it's a window of things to come in the future
You have to hit this issue HARD and FAST (imagine it's like bugs entering your very clean home for the first time) ...because once he's not satisfied with this anymore he WILL move on to other things..(bugs spreading / laying eggs)
May Allah (swt) protect your marriage from evil things and may you have a wonderful, joyful and happy life, inshallah.