Oops, sorry, I missed the thing about the baptism.
I personally would skip it--I don't think it would help you, and as RollTide points out, he will have others there for this special occasion. It feels a little too much like manipulation for him to want you there. Not that he is necessarily insincere about his "conversion" but he is the one who has fractured your relationship, and he really doesn't have the right to expect you to be there as if everything is just fine.