The Boy Who Sneaks in My Bedroom Window by Kirsty Moseley

Amber Walker and her older brother, Jake, have an abusive father. One night her brother’s best friend, Liam, sees her crying and climbs through her bedroom window to comfort her. That one action sparks a love/hate relationship that spans over the next eight years.
Liam is now a confident, flirty player who has never had a girlfriend before. Amber is still emotionally scarred from the abuse she suffered at the hands of her father. Together they make an unlikely pair.

Their relationship has always been a rocky one, but what happens when Amber starts to view her brother’s best friend a little differently? And how will her brother, who has always been a little overprotective, react when he finds out that the pair are growing closer?