Hi everyone, thank you for your (varied) thoughts
I went out for the day, saw a few friends, with the children, had lunch somewhere and had a good long think. Before I left I put the children in their car seats on the drive and had a 5-10min chat with H. He brought up trust (shockingly) and how if i didnt trust him, I was ending our marriage, I asked him to consider what he was asking of me. In the worst case scenario, he is grooming our son, in the best case scenario he is a fucking idiot.
He told me that he had pulled up an image on line while my son was on the other side of the room, got a bit excited, taken my phone and gone into the toilet to look at the same images and have a wank.
When i came into the room he stood in front of the computer and fiddled with my phone, he says coming off the website he had been looking at, he said that the reason he had come to the door was because I came down the stairs and he was just coming back in the room.
Anyway, I am not JUSTIFYING it (before anyone starts that again) I am just giving you the full story.
He told me, before I left that if he left 'it would be for good and i would have ended our marriage' I told him i accepted that if it protected our son.
He has nowhere to go, he will literally be on the streets tonight.
Anyway, as soon as he left (within 15 minutes of us returning) I called the NSPCC, which actually I had suggested he do with me. I spoke to a lovely man there and told him absolutely everything, he asked me a few questions about the relationship between my son and my husband and told me that in this situation, given that there is no previous cause for concern, CP would not be involved. He told me that what needed to happen, was for me to have a very serious chat with my husband about how serious this is, not just because of the looking at porn but also because he left our three year old in a room while he went and had a wank and that was irresponsible and neglectful. He said the police would not be interested at this time.
I asked him whether i should have this incident recorded and he said that at this time, there is no reason for that.
I am going to call my husband and speak to him when the children have gone to bed about what has been said and about how serious this is.
I will be keeping a very, very close eye on him, i dont know if i can trust him right now and if that trust is not gained by the time i have to go back to work I will be asking him to leave this house and arranging supervised visits with the children.
I am NOT taking this lightly, I am absolutely furious that he has put me in this position. I think he has been stupid and irresponsible and I imagine that wandering around in the rain (as he is now) is probably bringing that home to him in a big, big way.
Thanks again for the advice all.