OP, love, let's go through your posts and pick out the areas that are UN-FUCKING-BELIEVABLY indicative of a seriously abusive, and sick individual, one that should have NO contact with kids alone.
Huge issues with porn while he was in family home. He left DVDs lying around with pre-school children spelling out title words.
Exposing children deliberately to porn of any kind is deemed as child abuse. On pretty much the same level of perv that gets his kicks off kiddy porn.
Since he left he has given them iphones/tablets in his new home, on which they have internet access which he doesn't supervise. On one, I found clickable links to non-vanilla porn sites.
Ditto, see above, he is being wantonly reckless with his children and willingly exposing them to porn. That in itself is a SS matter as he's failing to safeguard his DC.
DC going to Dads this morning for overnight. As I dressed them, DS told me that last week when they were with Dad, they were downstairs while Dad was upstairs in bed with his new girlfriend (daytime).
He was fucking his GF, during the day, during an access visit. That is again child abuse, given the ages of the children, their mobility, and the above porn issues.
DC all under 10 so accept that whatever he does must be OK.
Except they KNOW it's not right, as they mentioned it to you. They are asking for your help.
Yes, thanks Cogito, I've started with the solicitor recently. But that in itself enrages him. As both he and his father warned me not to 'bring solicitors into this' when he left.
He has no respect for you, he has no feelings for you and furthermore threatens and allows/encourages others to intimidate and threaten you if you seek rightful legal counsel.
He is not following the norms of society, he sees that only he is entitled to having HIS needs met, to the exclusion of all others. he doesn't care about anyone or anything except his own sexual/power gratification.
Was he sexually abusive to you too?
Stop access visits, get advice, speak to every bloody agency there is. Your GP, your HV (if you have under 5s) The schools, the police DV unit, SS, everyone and anyone.
Get legal advice on withdrawing access, or insisting that it takes place in a contact centre as he can't be trusted not to abuse them.
I know you have lived with this for a long time, I know that he'd conditioned you to believe that you are the nutter, the freak, and in the wrong, but love, please, look at the replies here, not one of us is saying, chillax, you're making a fuss over nothing.
This is weird shit love. You are the only one that can protect your children from this vile and abusive 'man'.