@snowystar
I hope you and the DCs are ok. What a shitty thing. I am so glad you got legal advice so you know where to start. IMO, you are doing the right thing to take a breath allow the DC to adjust to new home life . At least to make sure you are coping on the changes and get a gauge your own mental health.
While many as saying the kids will adapt, it will be fine. You may find it it simply not the case and it can be punishing to your own mental health. As I have said previously, my 10 yr old took about the whole school year of extra tutoring/family help to get their maths confidence back.
I definitely could not imagine bringing a high schooler over without understanding that it may take considerable support from you (either personal time and effort or paid tutoring) to get over that gap half a year. Of course, they may simply breeze through and then you are all good.
In my DC case, don’t feel ‘exotic’ and ‘cool’ at all. They often feel like an alien to the point they even had their form in year 8 tell them they pronounce everything incorrectly- including emu (what the actual f!!!). We are hoping year 9 is the key. It will be 4 years and we ourselves found at that mark previously that we felt like U.K. was home. So, yes while your DC might again acclimate immediately, it may well be very helpful if they start off without having to deal with a fresh and maybe raw pain of the family break up.
Also, something to take into account which no one mentioned here is that AU$ that he pays in support may not cover quite as much. Maybe, that can be something you can research over the Chrissy break so you know exactly what it covers and make plans.
Look as far as everyone talking about being ‘stuck’ when they are adults. You must realize that while it is a nice thought to be around their adult selves, I cannot believe that making a decision on where you live based on the country they live is wise. You need to make that decision based on you and your needs if they are adults. Full stop!!! Don’t fall into that trap.
Whichever decision you make will be the right one if you make it with as much information and advice as you can. Even quick decisions can be good if they are well thought through and you don’t go into it blindly.
As everyone says though, he was totally in the wrong. Please don’t be made to feel that your actions made him have an affair. It was all him!