I split up with my children's dad about a year ago and we have both moved on and have new partners. My ex's new gf doesn't have children but is really good with mine and they adore her which I am grateful for. However, recently when they see her the first thing they do is say 'boobies' and prod them. She wears extremely low cut tops and has a very full chest. I am sure I even saw some nipples on Christmas Eve. It has worried me for a bit so I talked to my children (aged 3 and 5 so very young still) about privates being private and showed them the video on the NSPCC website. I am a primary school teacher with years of safeguarding training and I am very honest about these things. Yesterday when they came to collect the children the same thing happened with my 5 year old. So in front of the gf I said 'remember we had this conversation about privates being private. You shouldn't touch somebody else's breasts as they don't like it. But if your breasts or vagina hurts you must tell us so we can help.' I think she thought I was being abrupt (I am very blunt sometimes) as she said 'ohhh it's ok.' In my head I was screaming really no it's not. How do I bring this up with my ex? I would really like her to dress more conservatively around the children but appreciate everybody has their own style and choice of attire. I don't want to word it in a say that will cause offence but it makes me so uneasy. Thanks