SOLVED. A book involving evil entities and baseball. [s]

[Mattie]

I am searching for a book that I read in my childhood. I have been posting a summary of the plot all over the internet but I have been unsuccessful in finding it anywhere. Spoilers ahead for the ending and what happens during the story.

It is about this young boy, possible either in middle school or just starting high school, who often plays baseball with his good friend and a bunch of other boys in the neighborhood. He lives with his grandfather and mother (possibly) while his father is gone from his life. The protagonist is told his father left when he was born (?). The protag and the good friend he plays baseball with end up getting involved in some drama that happened in the past with some folks in their small town, eventually leading them to meet a girl who is the daughter of the mayor (or some high government man close to the mayor in power). The unique thing about this story is how it all led to this. The protag was walking home one day when he felt a strangeness in his stomach and discovered that some entity was attached to him. This entity may have been a dead person (I am sure, because the townfolk drama involved finding his body or unveiling how he died), and he came to the protag because it involved his father. Even the protag's grandpa was involved because the entity possessed(?) the protag and made him attempt to kill his grandfather (unsuccessful because the protag's close friend stopped him).

In the end I think it was revealed that the girl's mayor father and other people in town were responsible for killing the entity. Something happened with protag's father where he was forced to leave the town because of the murder. I remember there being a part in the story where the protag learns that his father wasn't actually a deadbeat and had actually loved him, often taking him to breakfast when he was a toddler. The entity left the protag alone when he refused to be controlled by him any longer, and later on the protag learns that his father died as a result of the entity attaching to him and making him drive off the highway. Protag's grandpa and mom are sad and guilty to say this to him, but I do not remember if they told the truth about the father or if the protag said he knew the truth. It finishes with the protag getting a ghostly visit from his father who says he often went back to town in secret to watch him grow up.

If anyone knows of this book, please inform me. It has been on my mind since I read it back in elementary (so it had to have been published before 2010) and I highly love it. The book cover had a baseball/baseball glove on a table and showed a window looking outside at the street below. It is possible the title is a street name or something similar. Thank you.

[[EDIT: Thanks to the extremely helpful Ayshe, I learned that this book is The Dreadful Revenge of Ernest Gallen by James Lincoln Collier. Thank you! My day has been made!]]

[Ayshe]

The Dreadful Revenge of Ernest Gallen by James Lincoln Collier seems to match?

[Mattie]

Ayshe wrote: "The Dreadful Revenge of Ernest Gallen by James Lincoln Collier seems to match?"

Wow, you are amazing. A life saver! Thank you! I have been looking for this book for forever, and I'm so grateful for your help once again. A million thanks, Ayshe!