Tell The Wolves I'm Home by Carol Rifka Brunt

This is really a Young Adult book, even though it was not shelved that
way at my local library.  The theme is sibling rivalry and the quest
for love and support within your family.  The Elbus' are very keen on
each other, and it leads to the kind of trouble you might imagine.

The year is 1986, and June Elbus is a shy 14-year-old living in the
New York suburbs with her accountant parents and increasingly
disruptive older sister, Greta. June's best friend is her beloved
Uncle Finn, a Manhattan painter in the final stages of AIDS. When Finn
dies, June's family seems more angry and embarrassed than bereaved,
making her feel alone and abandoned in her grief.

June has a nice balance of disarming candor and the melancholy
wisdom--she is truly on the cusp between childhood and adulthood.  I
think that having a significant person in your life die when you are in childhood brings about a certain kind of maturation, one that can either be a blessing or a curse.  You can handle it well and move
forward in life with a knowledge that is hard won and valuable, or you can handle it very badly and sink into all sorts of traps, like depression and substance abuse.  June seems to be on the right path,
but she needs help and her family is not providing it.

June's recourse is to surreptitiously befriend Finn's boyfriend, Toby, whom her family has shunned—they believe he infected Finn with HIV, and he is himself dying. With Toby's help, June uncovers the wounds that beset her family, including the old jealousies between her mother
and Finn and the antagonism between June's sister and herself. The intricacies of family relationships and jealousies are well handled in this novel, and it is a very fun read (which I know sounds surprising, given the material, but really, it is).