Opinion: Don't.
Seriously. If your marriage didn't work out. It did so for a reason. Sex will complicate a relationship you must maintain for your children's sake. You can try to rationalize, you can tell each other that is it "no strings" but in my experience, the women who claim it and those that can actually live with it are sure a different number. It is the same for me. Given your circumstances, you may well end up hurting yourself, your relationship with your ex, and your kids. All in all the risks are too high, it would be better to find someone new to play with.

Very early on,like before you two have stopped living together and DEFINATELY before either of you begins dating again.....I say it can be a beautiful way to bring closure to the whole affair. Please understand you both may be very emotional and may cry.It can be very intense and also open up a whole new dimension to the current dynamic,so be warned.The couple involved must,ultimately,make this decision for themselves.It can,and will,confuse things however so be prepared for this aspect. As a sheer physical relief and outlet it can remind each of you of better times and also maybe some of what it was that initially attacted you to each other. Sex with the ex further down the road will mess with both of your heads and....the kids know what is going on,even if they don`t understand it or can`t communicate it.

Hos

When it comes down to it if you will ....
All humans are ANIMALS ... feeding self-indulgent desires whenever with whomever wherever etcetra ...

SIGH .

This is so crazy because I am currently in this situation. ANd it's very far into the break up. But so far I have to say that it's been great and yes, I did cry. And yes, it's brought on a bit of confusion. But I think that we're finally at a point in our lives where we can both be mature and respectful about it. I of course am not with anyone else and neither is he, and neither one of us is denying it, so I can't totally relate. It's easier for me to distance myself from it though, because he only comes down once a month. ANd I am positve that our daughter knows nothing aobut it. we are very discreet. ANd so far, nobody's been hurt by this. I get a little bummed after he leaves for a day or two, then I'm happy to go about my normal routine which would totally be complicated were he here. I think it's totally an individual thing. In your situation I doubt if I would. It sounds like your ex may really like the thrill of cheating. Or maybe she just really still has feelings for both of you. ? Sounds complicated. As is life. Fun, fun!

I have a bit of spin to this. I have been married twice. I am currently working on my second divorce. Both wives were unfaithful and cheated.
With that said, here's my take. I would normally say "NO! It's not worth it!" But then again I fell into this situation and did the very thing I swore I wouldn't.
After not seeing my first ex for almost 4 years, she all of a sudden showed up at my house. All of those old emotions and feelings came with her. She apologized for the way things ended between us and we talked for hours and found some positive closure. Through all of this I found out she had remarried. Without thinking about it I put on the old charm and had some great ex sex. I know I shouldn't have had sex with her, hell she was married. I just figured WTF. If not me it'll be someone else. The point of view of the cheated on. That and it had been a 3 year dry spell. Call me a bad person for it. I call it - good sex.
As for the second wife I wouldn't touch her. God knows where she's been. Okay still bitter.
Either way ex sex can be great - but the key is to not get caught up and all emotional about it.

I wouldn't touch my ex, god knows where he's been!