Next part of the script is him turning into someone whom you just don't recognise.
When people get together, they nearly always modify their behaviours slightly around their partners, suppressing the bits that don't work so well in the relationship, enhancing the bits that are good. When the relationship ends, there is no longer any need for these modifications, so all the behaviours that didn't fit your relationship can come out - and they might shock you rigid.
I may have said this before, it bears repeating - always always assume the worst case scenario will happen. That way, you'll never be shocked, you might be pleasantly surprised, but you will be prepared.
Do not underestimate how low they can go - perhaps read other threads in here from women who are further down the line - whatever he agrees to in the first throes of guilt at breaking up the family, he will try and rescind in the next few months as the guilt wears off and you just become some annoying ex who won't just disappear into the past. Obviously you can't because you have children with the twat - so you HAVE to stay in touch, and he should bloody well be supportive of his children - but that does rather take the shine off his new super-duper "freedom" with the OW and he will resent it like fury as time goes on.
Sort out your finances, get yourself protected as much as you can as soon as you can - because they get sneaky really quickly, especially if the OW is the sort to whine about how unfair it is that he has to give so much money to you rather than them being able to enjoy it together - get some kind of agreement in place as quickly as you can too.
And as PPs have said, he might, after about 3m, call you saying he's made a terrible mistake and he's not sure he did the right thing and he still loves you - and you'll get all hopeful that he's changed his mind, got fed up with OW and is coming home - and the next time you talk to him he's completely gone the other way and is all loved up with Her again and it's like the WORST cold shower ever. (Experience talking here!)
At all times now, do what is right for YOU and your DC. His problems/affairs are HIS to worry about, you no longer need to. If he doesn't like whatever suits you, too bloody bad. He lost the right to have a say about that when he shagged Miss Lovebite.
I am sorry he's following the usual faithless bastard script, but at least you can be pre-warned as to what's likely to happen next.