YA Supernatural Teenage Girl Lives with Relative and discovers secret in attic

I am looking for a book that was most likely published somewhere around 2010 with the boom of YA Supernatural series. This was a stand alone book.

What I remember is that there is a teenage girl who has moved to live with her grandmother/great aunt/aunt (?) in a large house. I think it may have been on a coast somewhere. The girl can see ghosts or has some awareness of spirits. There was also a neighbor boy who ended up being her romantic interest and ultimately helps her figure out the supernatural stuff. There was a hint of something evil or bad happening to her family/in the house in the past. I think she went looking around the attic or a storage space and found a picture or an object that explained to her what happened. Her uncle ended up being the evil one. I have a vivid recollection of her learning this fact and then the uncle showing up to the house pounding on the door and flipping out, confirming that he was crazy. Her and the boy defeat him somehow.

It ends with her and the guy on the beach together. She is working as a lifeguard.

Thank you!