You both have had time to grow up since you split up. You married! If you want to put that at risk just for an adventure because she thinks that she wants something different, then please reflect back on the years you invested in your marriage.
You probably kept in contact with her, and have heard her side of the story, maybe she's not happy, but you'd better make sure that you know what you want before going with her.
If you don't care for your wife as you should, you should first tell her by explaining that she was second choice, and that you've been secretly waiting for the other one to come back (for what reasons - you only know). Because this is what you'll be doing, you'll be
calling it quits with your wife... or do you expect her to stay in the dark, waiting patiently for you to make up your mind as to what you want in life.
YOU OWE your wife more respect than this, so get off your high horse, your selfish way of thinking, and be straight with your wife first, before going on a trip with someone that will probably dump you once she is reassured that all she had to do was click her fingers and you'll come back after all these years, and don't remember reason you split, after that weekend she'll probably dump you again.
So, don't think that just one weekend will make all the wonderful things come back, she's probably testing the waters to reassure herself that she's still desired by you and other men before she goes out on her own to meet new people.
If you're willing to risk all that you've built up in the last four years, just for a fling, go ahead. If not, then tell her to pick on some other shmuck to test the waters and that you are not interested in helping her find out if she's still desirable.
I sure hope that you come to your senses and consider what all is at risk instead of letting your testosterone and/or ego lead the way to disaster.
Hope you don't find these words too harsh, but somebody had to wake you up, and I hope this helps you make your choice.

Cats are curious, but CAUTIOS, you should be the same...