YA Woman babysits quiet boy, mysterious family, frozen pond is key

[fancifuldelights]

2010 or earlier-This book takes place in winter and a young woman is hired to babysit a quiet boy and they bond. The boy’s parents (I assume) are dead (under suspicious circumstances) and he lives in an old castle with an old woman and other family members and now the young woman. She isn’t liked by the family (they’re very mysterious) and they try to poison her by giving her a (cherry?) pie slice with poison but she doesn’t eat it. She ends up falling in love with a young man (not sure how they meet but he visits often). The two are chased by an assailant with a gun (possible shootout and they hide behind some stone pillars?) but they get away. There’s also a great pond surrounding the castle, there’s a lot of fear surrounding it (I believe the boy is afraid/there was an incident on the ice/drowning?) and someone falls through/left on the ice as punishment and the boy plays ice hockey on it I think. The young woman warms the boy up after he falls through? Thank you for reading and for any titles you suggest!