If your Wife knows this is your Ex then you need to tell her why you feel uncomfortable, even if you parted on good terms. Failing that you become best friends with one of her old Boyfriends and see how she likes it.

You just know they're talking shit on you. FYL

that's seriously complicated! Good Luck OP.

One would think that'd be awkward for your current wife

Sounds like your life is gearing up to be one of THOSE reality shows.

If you have kids with your ex then consider it a good thing! My mother and step mother also get along unusually well and it just makes things so much easier for everyone. You don't have to deal with any unnecessary drama or awkwardness that the kids are inevitably dragged into and you can see each other at birthday parties and school functions without any issues. But if it seriously bothers you then maybe have a chat to both of them

Does she know you re-married? If not it shouldn't really be a massive issue

granted it's a weird friendship but it's better than them arguing and if you and your ex have kids together it's better for them if they see them getting along, however I am curious on how they decided to be friends I think this FML needs a follow up.

FYL for sure!

is it intensional or unknowingly!!!