eggplanty,
First of all, this is a male perspective, and you have my complete sympathy and you have done absolutely nothing wrong.If he's gone off an sought out this sort of thing without ever talking to you about what's making him do it (perceived lack of intimacy maybe - not saying that's acceptable, but there is a small amount of sympathy for a husband or wife who has tried and failed to resolve a lack of intimacy etc. but that doesn't appear to be the case here) so I just don't understand why he's done it.
I've been puzzling as to why anyone would even go to these sites. As has been said before, there's plenty of free porn out there if that's his thing (I think LTB for watching free porn is way over the top). But this is different, I think it may be even worse than a one off drunken visit to a prostitute (which is still LTB territory but at least there's a shred of justification that it was one moment of bad judgement) This has been repeated and has cost money the family doesn't appear to have. I don't think i could live with myself if I had to tell my children we couldn't afford a toy when I knew full well I'd spent family money on this sort of thing.
I'm also a child of divorce (mums fault as it happensif I could go back in time and reverse the divorce I would, even now in my 30s the divorce causes hassle (if I visit mum then I have to see dad around the same time or they moan and vice versa). BUT I have a way better relationship with my parents than many friends who's parents "stayed together for the kids" and raised their children in a house with an toxic atmosphere. If you are truly never going to be able to forgive this (which would be understandable) or you think he won't ever stop then it's of no benefit to the children at all.
It's just my perception, but I read a lot of these threads and often can see both sides or I get a vibe from the poster that there is some responsibility on their side or we aren't getting the whole story. I don't get that at all from you at all and you just seem a very nice person and great mum who is in a horrible situation that's come out of nowhere.
From all of that waffle, I want to repeat this isn't your fault and you should feel no shame. If possible (which is going to be tough) try and look at him as pitiful and that what he's done is the act of a pathetic saddo. you sound a bit like you are too busy trying to blame yourself to step back and thing "what a twat". That might make it easier for you to talk to your parents and get the truth out there. What he's done is shameful, nothing you've done is shameful.
From the more recent posts, I think you need to take back control.
My advice would be to tell him that the divorce stuff is on the backburner now and you just need time to calm yourself and think about things. That will hopefully make him think he can navigate through this and slow down him taking steps to try and control the divorce process.
Main reason for that is your bump. That's priority now and so is your health. As hard as this sounds, try and get in the mindset that he's the idiot not you and focus on you for now. If you feel the same way next week, next month, then you can still go back to the divorce. I don't think it's probable, but this might be the wake up call he needed and you at least retain some options.
Once again, this isn't you. The blokes a cretin and if the end game is his sorry arse gets kicked out YOU WILL BE OK in time. Dont get bogged down worrying about the financials, that just blurs judgement. Trust me, he will suffer financially more than you if you end up down that route. Right now work on getting stronger and looking after you DC and the bump.
Sorry that's a rambling waffle and sorry there's blokes out there giving the rest of us a bad name! Thoughts are with you and I'll keep an eye on this thread. No pressure at all but if you've got any questions that a less idiotic bloke can help with I'll reply to any PMs, though it looks like you are in good hands on here. Occasionally there's a few MNers who cause more harm than good, but you seem to have got the good uns on your side in here (more evidence that it's not your fault!)
Take care