Drunk teenagers shagging in a field - sounds about normal. The fact that he started ignoring her straight after shows what a dick he was, and that he probably just wanted to bed her when she thought they were real friends.
He's really lucky she didn't sell her story years ago, she came across as a nice person. What an awful predicament he's put her in now, selling their private moment for sensationalism and money (using her a second time)...what a dick!
She doesn't have the means to protect her family from the media onslaught, she's doing the best she can by trying to get her story out there on her terms and hopefully earn a bit as well.
I'm sure she feels completely betrayed. The more we know about Harry the more we realise what a thoroughly unpleasant man he is.
I would imagine working with horses wasn't paying the bills etc, and the hours not great, now she has a family to help support.