They might just be friends or they might be madly in love. There's no way to know and you could drive yourself mad guessing.
It doesn't change what you need to do, in truth it will only matter if and when she wants to reconcile (assuming he's not really bad for your kids that is) so in the meantime let it go.
And yes I do know how completely hypocritical I'm being but its a lot easier to say than do.
Both mid 30s, 2 young kids BD 7sep14 XW moved on long ago, now living with OM1 D paperwork in progress
