All the best.
My ex left in 2008 (wow, that's 6 years now). I'm not sure whether he was involved with his current DP at the time, but they were certainly friends, I didn't know about their relationship until his told me nearly a year later because he planned to introduce the kids to her.
We separated, he moved out. I saw a solicitor for a free half hour with the intention to instruct when it was all very raw (days rather than weeks or months). I also researched online and as I was the one who deal with our finances I was aware of what we had etc. In the end, after trying to persuade him to try again for a number of months, we agreed finances etc between us.
We only actually divorced 2013/14, at first I hadn't wanted to, then I just didn't deal with it - I'm not sure why he didn't push it. I did the divorce paperwork myself, the actual divorce is very easy - it's the finances, and maybe children, that can cause issues. We did 2 years agreement, although by the time I did it if I had waited another couple of months I could have done 5 years! I then saw a solicitor to get the consent order (finances) drafted on the basis we had already agreed and lodged that with the court myself as well.
If you can (both) put your differences to the side and agree things between you it is almost certainly going to be easier than litigation, but you also have to ensure it is fair (to you both).
I really feel for you, I was 36 with two young children and had been with H for 16 years. I really didn't see how I would cope, despite the fact that I had been coping while he was away a lot etc. It's the end of something you anticipated being forever and it's very hard.
BUT I'm actually happier now than I had been previously for a number of years. I personally wouldn't have chosen this course, but having had it forced up on me I have moved on, and done my best to ensure that my kids have coped with it as well as possible.
Be good to hear how you get on tomorrow.