Dp just rang on his long drive to work to agree with my proposal about splitting up.
We have been together over 10 years and have 3 dc's under school age.
I'm not shaking, i'm not crying, i haven't got the sick feeling in my stomach. In fact, i feel them when we are trying and i'm waiting for him to fuck up. 
I just don't trust him. Or have any respect for him. Things have come to a head in the last few weeks, because i have give him an ultimatum about his porn use.
I had picked up his phone to ring him on his work phone (which he had on him) i scroll though logs to find work phone and see a text from 'julie' i look in messages, no messages, i look in contacts, no julie under names. But it said 'julie' and not a number on his log. I spend the next 2 hours with my heart beating in my chest and feeling physically sick that he is cheating, before i can confront him. He says it was a porn text.
I had reluctantly conceded to him using porn when he was away, (for the last 10 years) but I have always hated, had problems with it, (as my ex was a massive porn addict)
So i had a big conversation about it and he had promised not to do it and then less than 3 weeks later i went to use google on his phone (he handed the phone to me) and the idiot had not closed down his incognito page (i wasn't even snooping) I told him that he had promised and he said did i? My bad.
So, for the 1st time ever an ultimatum was given. I asked him last night if he had kept to it and he wouldn't answer. Kept saying, why do you want to know, what does it matter? etc. That he his not answering because i always have an hidden agenda etc. Ie, i usually find out the answer before i ask to see if he still lies.
I went to bed a couple of nights ago before him and woke to find a wank tissue on the kitchen floor. yuk. He leaves them by the bed sometimes. I've told him i see it has passive aggressive and i've had enough. It's not wanking i have a problem with. It's the constant feeling that he is doing it to other women.
He use to have a rented house and only came home at weekends and once when the internet was down, i went on his phone to mumsnet and when i typed in m, it brought up loads of porn pages (before incognito) so i looked at his history and he had looked every day of that week. He says he's just bored, it helps him sleep.
I say i'm sick of feeling insecure, paranoid and not trusting a word he says.
I'm waiting to break down. I feel so sorry for my children.
I feel like i keep swallowing down problems, but i can't do it anymore. My mum is not supportive and makes excuses for him, says, ignore him, let it go etc.
I think she just doesn't want me to be on my own. But he doesn't give me any money (says i can just use his card anytime) so i would be financially better off anyway. To make it worse we are moving house in a few weeks. It is in his name only.
Christ beginning to wish i hadn't wrote this has the enormity is hitting me and the tears are coming. Not good.
Please help.