ex text me about 12 year old daughters dirty text messages?

[saxons_uk]

My ex wife text me last night asking me if I would have a word with my daughter , she has just turned twelve, she said that when she stayed at mine at the weekend, she was texting some boy/man late at night after I had sent her to bed, the text said things like (Are you fingering yourself and send me pics of you in your bra).
The ex wife said that she had confronted her about it, but said she just clams up and walks off. Just don't really know what to do or say, is given the number to the police a bit extreme?....tried ringing the number but getting no answer....I know that she is intitled to her privacy and the ex shouldn't really be going through her phone, confronting her in the wrong way might also make her rebound. After the horror stories of the past news events, we tend to think the worse, it might just be a young lad at school messing about, but she is on msn, twitter, facebook and bebo all the time, there is no stopping the children doing anything now days. Please advise, she is just still my little girl in a womans body.