Homecoming Massacre (2020) on Netflix

Plot summary

On his seventh birthday, Jonathan saw a violent act committed against his mother, and the shock caused a mental collapse. Days later his aunt Mary found the boy at home, dressed as a clown, alone with his mother's body and that of her lover. Jonathan has spent a decade in a mental health facility. In that time Mary fought her own substance abuse and has stayed sober long enough to be forgiven by her husband and her teenage children. She decides her nephew deserves the same forgiveness and brings him into her household, hoping his life can be normal. As his seventeenth birthday approaches, the imaginary friend from his childhood comes out to play.