First of all - don't jump to conclusions. Just because he is finally stepping up to the plate to see his kids, may or may NOT mean he has any interest in reconciliation. Wait and watch.
Second - I think it is helpful to make a list of WHAT HE WOULD HAVE TO DO to make you feel totally secure in taking him back (should it come to that). The temptation is to just be so happy that they want to come back (again, assuming it comes to that) that the LBS takes them back without making the WAS do the work they need to fix themselves.
For instance - just as an example - I might want to see 6 months of consistent behavior with the kids, regular payment of adequate child support, regular therapy for substance abuse or depression or mental illness (nobody just walks on their kids like that without either a substance abuse issue or mental health issues). Maybe THEN, IF they agreed to total transparency around things like cell phones and email and finances, I might consider dating them.
Now, that's me - you might have different standards. But don't put yourself in the position of welcoming him back home without making him do the work - you'll just jump into a hell of insecurity.
(Plus, just a little warning - sometimes when they turn back up like this, it's because they're going to get married or have a baby and their new OW is encouraging them to reconnect with the kids. Not saying this is your sitch - it probably isn't - but protect your heart until you get a little more info. Does he give YOU any explanation for his sudden change in behavior?)
