Girlfriend had sex with a 24 year old when she was 15

I've been with a girl 5 months. She's lovely, intelligent and sweet. She really likes me and this is the longest relationship she's been in. Honestly she's brilliant. She never ever puts a foot wrong and if we argue it's usually because one of us gets jealous.. And it always ends well. To be honest she's probably way out of my league and easily the best girlfriend I've ever had. So what's the problem ? She has a past. she told me a little while ago she had sex with a 24 year old when she was 15. It wasn't a massive problem at first because she put it down to being drunk, not knowing his age and it being a spur of the moment. Later she admitted that she wasn't actually that drunk, she knew how old he was and it was a weekend fling.. Where she took him to her friends had sex with him.. Spent the next day with him and then had public sex again in the toilets of a bar. Yeah. I've seen the guy and apparently he didn't know she was 15 until afterwards ... I find that very very hard to believe. I don't know. It just doesn't sit right with me. It makes me feel uncomfortable and I keep branding her a "slut" in my head. I have a Christian background so perhaps that make things categorically worse. I really want to get over this but it's driving me away and making me feel bad whenever I think about it. Thought and advice? Please no bull**** ..

Put the internet to work for you. via Personal Recipe 2629979