Fighting Destiny question

This is a long shot, but I'm looking for a book mostly based in Ireland by way of Philadelphia. I don't remember the female character's name but her best friend's name is Marco. They lived in Philly, worked at a gay bar known for the singing and drag shows.
She found out that her mom kept information about her dad from her because the mom didnt' want her to know about her Fae family in Ireland. The mc and Marco take a trip to Ireland where she stumbles on her dad's family. To get to the fae world, they haveto go "thru" a tree.
And her dad was a member of a singing group in his younger days, her and Marci sings, while Marco plays and teaches a lot of instruments.
It's not a lot to go on but maybe someone can help me out.