This IS a tough spot to be in, but I think you are correct in that you need to quit trying to counsel her spiritually. That is what her pastor is for.
If I were in your shoes, I would --in confidence--call the pastor (you've spoken with him before, right?) and let him know you are thrilled that she has decided to be baptized, but you are concerned that she also seems to believe that this gives her license to sin, and because of God's grace, it will all be OK. Perhaps some additional pre-baptismal counselling by the pastor would be a good idea.
Let the pastor know that you and the children plan to be there to support her. Arrive early and sit in front. I think it would be a mistake to miss her baptism. Just my thoughts...
--Silverado
It is a tough spot. A very awkward one which creates huge conflicts within me.
I have considered calling the pastor, but haven't because then I would be meddling in something that my W must deal with on her own conscience. I imagine how I might feel if my pastor pulled me aside and said "I understand you have gone to communion without going to confession for this, this, this, and this." I would probably feel that my W was intentionally trying to spite me. If somehow my intervention caused them to refuse to baptize my W, I could see how she would hold it against me when really it is none of my business.
They do have a preparation class at my W's church that baptism candidates must attend. I hope that they cover topics like this, especially regarding repenting from sins, but who knows. My W would probably feel that the baptism will wipe away the sin and she can start over. Though we won't be divorced by then, so her first act as a Christian will be to continue in committing one of the biggest sins of all.
Maybe the OM would feel intimidated by my presence and beg out of it. I am hoping my in-laws come to put more heat on him. I can see my mother in law giving him the evil eye. They are not Christian and don't practice any faith, so they see this whole change in their daughter very cynically.
WAW Using God Me-43 W-40 M-14 S-11 S-9 D-7 EABomb 5/09 Separated 12/09