Barely 9 and my 6 yr old touching

My boyfriend's 9 yr old (just barely) touched my 6 yr old daughter by squeezing her butt and putting his hand over her vagina.  All of this was over the clothes.  They may have been discussing being boyfriend and girlfriend, and he may have used terminology like "I want to sex you up".  My daughter is almost done with her counseling and seems to be fine.  Obviously, we don't allow the kids to see each other anymore.  At my urging, the boy is now going thru his own counseling.  I have a hard time thinking this was just "playing doctor" due to his age and the areas he was interested in.  My ex-husband called child services and the investigators deemed it "child upon child" activity with no findings.  He is, however, taking me to court for custody of the children since I did not break up with the boyfriend.  Can my ex charge the boy with molestation?  Does anyone agree that this seems out of bounds for normal child sexual development?  Thanks